Class 10 Science: Chemical Reactions & Equations PDF

CLASS 10 NOTES SCIENCE Chemical Reactions & Equations PRASHANT KIRAD  PRASHANT KIRAD Chemical Reaction: The transformation of chemical substance into another chemical substance is known as Chemic...

CLASS 10 NOTES SCIENCE Chemical Reactions & Equations PRASHANT KIRAD  PRASHANT KIRAD Chemical Reaction: The transformation of chemical substance into another chemical substance is known as Chemical Reaction. e.g.: Rusting of iron, the setting of milk into curd, digestion of food, respiration, etc. JOSH METER? Chemical changes indicate that a chemical reaction has occurred. Characteristics of chemical reactions: Formation of new substances with different Chemical Equation: properties, Change in color, Evolution of gas, Representation of chemical Evolution or absorption of heat, Formation of a precipitate, Irreversibility of many chemical reaction using symbols and reactions, Change in state of matter, Change in formulae of the substances energy. is called Chemical Equation. Example: A + B → C + D D RA Reactant Product Magnesium + Oxygen → Magnesium oxide Mg + O2→ MgO KI Magnesium ribbon burns T with a dazzling white AN flame and changes into a white powder. This powder is magnesium H oxide. It is formed due AS to the reaction between magnesium and oxygen present in the air PR Magnesium is rubbed with sandpaper to remove the oxide layer, allowing it to burn more easily. Balanced Chemical Equation: A balanced chemical equation has an equal number of atoms of each element in the reactant and product side. Law of Conservation of Mass: Mass of reactants = Mass of products. Fe+H2O→Fe3O4+H2 (Unbalanced) 3Fe+4H2O→Fe 3O4 + 4H 2 (Balanced) number of atoms of each element in reactants = number of atoms of each element in products  PRASHANT KIRAD “Experiment ka funda“: Take some lead nitrate solution in a test tube or beaker and add potassium iodide solution. A yellow precipitate of lead iodide forms immediately, and the solution changes color from colorless to yellow. “Experiment ka funda“: Take some zinc granules in a conical flask and add sulfuric acid. Bubbles of hydrogen gas will form around the zinc D metal. We verify it's hydrogen gas because the bubbles burn with a popping sound when passed through a soap solution. RA Formation of hydrogen gas by the action of Additionally, the flask becomes hot to the touch, indicating dilute sulphuric acid on zinc that the reaction releases heat along with the gas. KI T Balancing Chemical Reaction: AN 1. Identify the unbalanced equation: H 2. List the number of atoms of different elements in the unbalanced equation: AS PR 3. Start balancing the compound (reactant of product) that contains the maximum number of atoms. In that compound, balance the element with the maximum number of atoms (Balanced) “Balancing ki practice jyaada se jyaada karo” - Prashant Bhaiya  PRASHANT KIRAD More Questions to practice: 1. CO 2 + H 2 O → C6 H 12 O 6 + O 2. A solution of slaked lime Ca(OH)2 is used for whitewashing walls. It reacts with carbon dioxide in the 2. CH4 + O2 → CO2 + H 2O air to form calcium carbonate CaCO3 , which gives the walls a shiny finish after two to three days. Marble also 3. Fe 2O3 + C → Fe + CO2 has the formula CaCO3 ​. The reaction is: 4. N 2 + H2 → NH 3 Ca(OH) 2 (𝑎𝑞)+CO 2(𝑔)→CaCO 3(𝑠)+H 2O(𝑙) Types of Chemical Reactions: 1. Combination Reactions: two or more reactants combine to form single products. A + B → AB 1. Formation of Water : 2H2 +O2 →2H 2 O 2. Formation of Calcium Oxide : CaO + H 2O → Ca(OH) 2 (slaked lime) D RA KI T “Experiment ka funda“: AN Take a small amount of calcium oxide (quick lime) in a beaker and slowly add water to it. Touch the outside of the beaker, and you will feel it getting hot. This is because calcium oxide reacts vigorously with water to produce slaked lime (calcium hydroxide), releasing a H large amount of heat. AS Reactions that release heat along with the formation of products are called exothermic PR chemical reactions, while those that absorb heat are known as endothermic reactions. 2. Decomposition Reactions: a single reactant decomposes to form two or more products. AB → A + B 1. Decomposition of Calcium Carbonate : CaCO3 (s) → CaO(S) + CO2 2. Decomposition of Ferrous Sulphate : 2FeSO 4 → Fe2 O3 + SO 2 + SO 3 Saari activities acche se dekhna, important h! Direct questions aa jaate h  PRASHANT KIRAD “Experiment ka funda“: Take about 2 grams of Ferrous Sulphate Crystals in a DRY Boiling Tube. They are originally green in color. Heat the boiling tube over a burner, and you will observe the magic. The green color changes to white and then finally a brown solid is formed, which is ferric oxide. Along with the color change, the smell of burning sulphur is also noticeable Thermal Decomposition Reactions: heat-induced breakdown. “Experiment ka funda“: Take 2 grams of lead nitrate powder in a boiling tube. Heat it over a burner. Brown fumes of nitrogen dioxide gas are released, filling the tube. Holding a glowing splinter over the tube causes it to catch fire, indicating the presence of oxygen gas. After the reaction, yellow lead monoxide solid remains in the tube, which appears reddish-brown when hot and yellow when cold. D RA Electrolytic Decomposition - heat-induced breakdown.. Activity 1.7: KI Hydrogen (cathode) will produce a popping sound when a burning candle is brought close. Oxygen (anode) will make the flame of the candle burn brighter. T Photolytic Decomposition - light-induced decomposition. AN “Experiment ka funda“: H White silver chloride turns grey in sunlight. This is due to the AS decomposition of silver chloride into silver and chlorine by light. PR 3. Displacement Reactions: chemical reaction in which a more reactive element displaces a less reactive element from its compound. Single Displacement: A+BC→AC+B Example: Zn+CuSO 4 →ZnSO 4 +Cu Reactivity series of metals Trick to remember reactivity reactivity series: Katrina ne car mangi alto zen ferari phir bhi haye cu mili silver audi  PRASHANT KIRAD “Experiment ka funda“: In this reaction, the iron nail turns brownish and the blue color of the copper sulphate solution fades because iron displaces copper from copper sulphate (CuSO₄) in a displacement reaction. The original deep blue color of the solution fades to light green, and the iron nail becomes covered with a red- brown layer of copper. 4. Double Displacement Reaction: Those reactions in which two ionic compounds in the solution react by exchange of their ions to form new compounds are called double displacement reactions. Double Displacement: AB+CD→AD+BC Example: NaOH + HCl → NaCl + H2O D “Experiment ka funda“: RA Take 3 mL of sodium sulphate solution in a test tube and 3 mL of barium chloride solution in another. Add the barium chloride solution to the sodium sulphate solution. A white KI precipitate will form in the test tube T AN Secret Questions: H 1. Write the balanced chemical equation for the reactions that take place AS during respiration. Identify the type of combination reaction that takes place during this process and justify the name. Give one more example of PR this type of reaction. [CBSE 2012] Solution : (i) The carbohydrates that we take in our food are oxidized to carbon dioxide and water. C₆H₁₂O₆ + 6O₂→ 6CO₂ + 6H₂O The carbon of carbohydrates and oxygen combine to form CO₂. (ii) It is an exothermic combination reaction. (iii) Decomposition of vegetable matter into compost is another example of this type of reaction. 2. Translate a balanced chemical equation with state symbols for the following i) Solutions of Barium chloride and Sodium sulfate in water react to give insoluble Barium sulfate and a solution of Sodium chloride.  PRASHANT KIRAD ii) Sodium hydroxide solution in water interacts with hydrochloric acid to produce Sodium chloride solution and water. iii) Hydrogen gas combines with nitrogen to form ammonia. iv) potassium metal reacts with water to give potassium hydroxide and hydrogen gas. Solution : i) BaCl 2 +Na2 SO4 →BaSO 4 +2NaCl ii) NaOH+HCl→NaCl+H 2 O iii) 3H2 +N2 →2NH 3 iv) 2K+2H 2 O→2KOH+H2 5. Oxidation Reactions: Oxidation: If a substance gains oxygen or loses hydrogen during a reaction, it D is said to be oxidized. RA Reduction: If a substance loses oxygen or gains hydrogen during a reaction, it is said to be reduced. KI Redox Reaction: In a reaction where one reactant gets oxidized while the other gets reduced, it is called an oxidation-reduction reaction or redox T reaction. AN “Experiment ka funda“: When about 1 gram of red-brown copper powder is heated in a china dish, it forms a black substance, which is copper H oxide (CuO). This black coating is a result of the oxidation of copper to copper oxide. To turn the black coating back AS to reddish-brown, hydrogen gas can be passed over the heated copper oxide, causing a reverse reaction that produces copper. PR “Ox“idation: “Ox“ygen dost (gaining oxygen) or Hydrogen dushman (losing hydrogen). “Re“duction: Oxygen dushman (losing oxygen) or “Hy”drogen dost (gaining hydrogen). { Hy re! } Oxidised (+O) ZnO + C → Zn + CO Reduced (-O) Extra Knowledge!!  PRASHANT KIRAD EFFECTS OF OXIDATION REACTIONS IN EVERYDAY LIFE? Corrosion: the process by which metals are gradually destroyed by chemical reactions with substances in their environment, such as moisture and acids. This often results in the formation of an oxide or other compound on the metal's surface. Impact: Corrosion weakens the metal structure, affecting its strength and durability. Prevention: Coating metals with protective layers (e.g., paint or galvanization) helps prevent direct exposure to oxygen and moisture, reducing the risk of corrosion. Examples: Rusting of iron, Tarnishing of silver, Green coating on copper Rancidity: the spoilage of fats and oils in food, leading to unpleasant D taste and smell. This happens due to the oxidation of fats and oils when RA exposed to air. Impact: Rancidity imparts unpleasant tastes and smells to food products, KI making them unpalatable and reducing their shelf life. Prevention: Adding antioxidants, storing foods in airtight containers, and T refrigerating can help slow down or prevent the oxidation process and, AN consequently, rancidity Examples: Spoiled butter, Old cooking oil, Stale chips H AS Top 7 Questions PR 1. Why is respiration considered an exothermic reaction? Explain. Answer: Respiration is the process of breaking down food in the living body to produce energy. Respiration is considered an exothermic chemical reaction because the oxidation of glucose occurs during the process, releasing a large amount of energy, which is captured in the form of ATP. During respiration, we inhale oxygen from the atmosphere, which reacts with glucose in our body cells to produce carbon dioxide, water, and energy. The reaction is represented by the following chemical equation: C₆H₁₂O₆ + 6O₂→ 6CO₂ + 6H₂O + energy ( ATP )  PRASHANT KIRAD 2. Explain the following in terms of the gain of oxygen with two examples each. (a) Oxidation (b) Reduction. Answer: (a) Oxidation: In a chemical reaction, when oxygen is added to an element or compound to form its oxide, the element or compound is being oxidized. For example: 4Na(𝑠)+O 2 (𝑔)→2Na 2O(𝑠) H 2S(𝑔)+O 2 (𝑔)→H 2O(𝑙)+SO 2(𝑔) (b) Reduction: In a chemical reaction, when oxygen is removed from a compound, the compound is said to be reduced. For example: CuO(𝑠)+H 2(𝑔)→Cu(𝑠)+H 2O(𝑙) 2HgO(𝑠)→2Hg(𝑙)+O2 (𝑔) 3. A shiny brown-colored element ‘X’ on heating in the air becomes black. D Name the element ‘X’ & the black-coloured compound formed. RA Answer: The shiny brown-colored element is Copper metal (Cu). If the metal is heated in air, it interacts with atmospheric oxygen to form copper oxide. KI Therefore, the black-colored compound is copper oxide. 2Cu(s) + O 2 (g) → 2CuO(s). T AN 4. Why do we store silver chloride in dark-colored bottles? Answer: Silver chloride is highly sensitive to light and undergoes photolytic H decomposition upon exposure to light. This reaction occurs rapidly and causes AS the silver chloride to lose its properties, forming chlorine gas and elemental silver. Therefore, silver chloride is stored in dark-colored bottles to protect it PR from light and prevent its decomposition. 5. Write one equation each for decomposition reactions in which energy is supplied in the form of heat, light, or electricity. Answer: (a) Thermal decomposition reaction (Thermolysis): Decomposition of potassium chlorate: If heated strongly, potassium chlorate decomposes into potassium chloride and oxygen molecules. This reaction is commonly used for the synthesis of oxygen molecules. 2KClO 3 +heat→2KCl+3O 2 (b) Electrolytic decomposition reaction (Electrolysis): Decomposition of sodium chloride (NaCl): On passing electricity through molten sodium chloride, it decomposes into sodium and chlorine. 2NaCl(electrolysis)→2Na+Cl 2  PRASHANT KIRAD (c) Photodecomposition reaction (Photolysis): Decomposition of hydrogen peroxide: In the presence of light, hydrogen peroxide decomposes into water and oxygen molecules. 2H 2O2 +light→2H2 O+O 2 6. What is the difference between displacement and double displacement reactions? Write relevant equations for the above. Answer: A displacement reaction occurs when a more reactive substance replaces a less reactive substance from its salt solutions. A double displacement reaction occurs when a mutual exchange of metal ions happens between two compounds. In a displacement reaction, only a single displacement occurs, whereas in the double displacement reaction, as the name suggests, two displacements occur between the molecules. D Example of Displacement reaction: RA Mg+2HCl→MgCl2 +H2 Example of Double displacement reaction: KI 2KBr+BaI2 →2KI+BaBr 2 T 7. Zinc liberates hydrogen gas when reacted with dilute hydrochloric acid, AN whereas copper does not. Explain why? Answero Zinc is more reactive than copper as Zinc is placed above hydrogen, H and copper is placed below hydrogen in the activity series of metals. Thus, zinc AS liberates hydrogen gas when reacted with dilute hydrochloric acid, whereas copper does not. PR Top 7 Questions 1) Clean a magnesium ribbon about 2 cm long by rubbing it with sandpaper. Hold it with a pair of tongs. Burn it using a spirit lamp or burner and collect the ash so formed in a watch-glass  PRASHANT KIRAD (i). Magnesium ribbon needs to be rubbed before burning because it has a coating on its surface. A. basic magnesium carbonate B. basic magnesium oxide C. basic magnesium sulphide D. basic magnesium chloride (ii). What is the colour of magnesium ribbon? A. White B. Black C. Grey D. Yellow (iii). What is the chemical name of the powder obtained in the D A. magnesium carbonate RA B. magnesium oxide C. magnesium sulphide KI D. magnesium chloride T (iv). Which compound is formed when the powder obtained reacts with water? AN A. Magnesium sulphate B. Magnesium oxide H C. Magnesium Carbonate AS D. Magnesium hydroxide PR 2) Take a plastic mug, drill two holes at its base and insert carbon electrodes. Connect these electrodes to a 6 volt battery. Fill the mug with water such that the electrodes are immersed. Add a few drops of dilute sulphuric acid to the water. Take two test tubes filled with water and invert them over the two carbon electrodes. Switch on the current and leave the apparatus undisturbed for some time.  PRASHANT KIRAD (i). What is the ratio in which hydrogen and oxygen are present in water by volume? A. 1:2 B. 1:1 C. 2:1 D. 1:8 (ii). Which electrodes are used in this activity? A. Graphite B. Diamond C. Copper D. Coke (iii). Where is hydrogen gas collected? D A. Anode RA B. Cathode C. At both electrodes D. Hydrogen gas is not evolved in this activity KI T (iv). Which of the following is an endothermic process? AN A. Dilution of sulphuric acid B. Condensation of water vapours H C. Respiration in human beings D. Electrolysis​ AS Answers: PR 1. (i) A (ii) C (iii) B (iv) D “Class 10th Phodenge” 2. (i) C - Prashant Bhaiya (ii) A (iii) B (iv) D  CLASS 10 NOTES SCIENCE Acids, Bases and Salts PRASHANT KIRAD  PRASHANT KIRAD Acids and Bases Acids Bases Sour in taste, Derived from Greek word Bitter in taste. “Acidus”. Changes blue litmus into red. Changes red litmus into blue. e.g. Sodium Hydroxide (NaOH), e.g. Hydrochloric acid (HCl), Sulfuric acid, Potassium hydroxide (KOH), Calcium Nitric acid, Acetic acid, etc. Hydroxide, Ammonium Hydroxide, etc. D RA Acid-Base Indicators: Natural indicators like litmus, turmeric, red cabbage leaves, and colored petals from KI flowers like Hydrangea, Petunia, and Geranium can show acidity or alkalinity. On the other hand, synthetic indicators such as methyl orange and phenolphthalein are also T AN used for the same purpose. Red litmus solution Blue litmus solution Phenolphthalein solution Methyl Orange Solution H AS Acid - No change Acid - Red Acid - Colorless Acid - Red Base - Blue Base - No Change Base - Pink Base - Yellow PR Some naturally occurring acids: “” - Prashant Bhaiya  PRASHANT KIRAD What Is an Acid and a Base? EMA Ionizable and Non-Ionizable Compounds An ionizable compound, when in water or molten form, breaks down into ions almost completely. Examples include NaCl, HCl, KOH, and others. In contrast, a non- ionizable compound does not separate into ions when dissolved in water or in its molten state. Examples of such compounds are glucose and acetone. Acids and Bases An acid is a substance that contains hydrogen and can donate a proton (hydrogen ion) to another substance. On the other hand, a base is a molecule or ion capable of accepting a hydrogen ion from an acid. Typically, acidic substances are recognized by their sour taste. Arrhenius’ Theory of Acids and Bases An Arrhenius acid is a substance that, An Arrhenius base is a substance that, when dissolved in water, breaks apart to when dissolved in water, dissociates to D yield H+ (aq) or H3O+ ions. produce OH− ions. RA Acids Bases Hydrochloric acid (HCl) Sodium hydroxide (NaOH) KI Sulfuric acid (H2SO4) Potassium hydroxide (KOH) Nitric acid (HNO3) Calcium hydroxide [Ca(OH)2] T AN Bronsted Lowry Theory A Bronsted acid is an H+ (aq) ion donor. H A Bronsted base is an H+ (aq) ion acceptor. AS Examples: In the reaction: HCl (aq) + NH3 (aq) → NH+4(aq) + Cl− (aq) PR JOSH METER? HCl – Bronsted acid and Cl− : its conjugate acid NH3 – Bronsted base and NH+4 : its conjugate acid Potential physical tests for identifying an acid or a base are: Taste Acids typically have a sour taste, while bases often taste bitter. However, relying on taste to identify acids or bases is not recommended due to the risk of contamination or corrosiveness. For instance, substances like curd, lemon juice, orange juice, and vinegar exhibit a sour taste because they contain acids. On the other hand, baking soda, despite having a somewhat sour taste, serves as an example of a base. It is essential to use proper testing methods rather than relying on taste alone. Effect on Indicators by Acids and Bases An indicator is a chemical substance that exhibits a change in its physical properties,  PRASHANT KIRAD particularly in color or odor, upon contact with an acid or a base. Common indicators and the colors they display are as follows: a) Litmus: Litmus is provided in paper strip forms as red litmus and blue litmus. Neutral solution – purple Acid transforms moist blue litmus paper to red. Acidic solution – red Base transforms moist red litmus paper to blue. Basic solution – blue b) Methyl Orange: Neutral solution – orange Acidic solution – red Basic solution – yellow c) Phenolphthalein: Neutral solution – colorless Acidic solution – remains colorless Basic solution – exhibits a pink color. EMA D Acid-Base Reactions RA When acid and bases react with metals: Acids, in general, react with metals to produce salt and hydrogen gas. Bases, in general, do not react with metals and do not produce hydrogen gas. KI Acid + active metal → salt + hydrogen + heat T 2HCl + Mg → MgCl2 + H2 (↑) AN Base + metal → salt + hydrogen + heat 2NaOH + Zn → Na2ZnO2 + H2 (↑) H A more reactive metal displaces the less reactive metal from its base. AS 2Na + Mg (OH) 2 → 2NaOH + Mg When acid react with Metal Carbonates and Bicarbonates: PR When acids engage with metal carbonates or bicarbonates, the resulting reaction generates carbon dioxide, metal salts, and water. For example, the reaction between hydrochloric acid and sodium carbonate produces sodium chloride, carbon dioxide, and water. Notably, if the evolved carbon dioxide is passed through lime water, it causes the lime water to exhibit a milky appearance. Acid + metal carbonate or bicarbonate → salt + water + carbon dioxide. 2HCl + CaCO3 → CaCl2 + H2O + CO2 H2SO4 + Mg (HCO3)2 → MgSO4 + 2H2O + 2CO2 Effervescence indicates the liberation of CO2 gas. When acid and Base react with each other: A neutralization reaction takes place when an acid interacts with a base, resulting in the formation of salt and water as the final products. In this conventional approach, an acid- base neutralization reaction is expressed as a double-replacement reaction. Acid + Base → Salt + Water  PRASHANT KIRAD 1.Metal Oxides and Hydroxides with Acids: Metal oxides or metal hydroxides exhibit basic properties. Acid + Base → Salt + Water + Heat H2SO4 + MgO → MgSO4 + H2O 2HCl + Mg (OH) 2 → MgCl2 + 2H2O 2.Non-Metal Oxides with Bases: Non-metal oxides demonstrate acidic properties. Base + Nonmetal Oxide → Salt + Water + Heat 2NaOH + CO2→ Na2CO3 + H2O Reaction of acids and base A very common acid is hydrochloric acid. The reaction between strong acid, says hydrochloric acid and strong base say sodium hydroxide, forms salt and water. The complete chemical equation is shown below. HCl (strong acid) + NaOH (strong base) → NaCl (salt) + H2O (water) D Acids and Bases in water RA When added to water, acids and bases dissociate into their respective ions and help in conducting electricity. KI Acids: Ionization: When an acid is dissolved in water, it ionizes to produce hydrogen ions (H⁺). T These hydrogen ions combine with water molecules to form hydronium ions (H₃O⁺). AN H⁺ + H₂O → H₃O⁺ Bases: Dissociation: When a base is dissolved in water, it dissociates to produce hydroxide H ions (OH⁻). AS Heat NaOH → Na⁺ + OH⁻ PR Bases which are soluble in water are called alkalis. All bases do not dissolve in water. They are soapy to touch, bitter and corrosive. What are alkali? Dilution: Dilution involves decreasing the concentration of a solution by incorporating additional solvent, typically water. This process is highly exothermic. When diluting acid, it is essential to add the acid to water and not vice versa. Strength of Acids and Bases: Strong Acid or Base: In the case of a strong acid or base, every molecule in a given quantity undergoes complete dissociation in water, resulting in the formation of their respective ions (H+(aq) for acids and OH−(aq) for bases). Weak Acid or Base: Contrastingly, with weak acids or bases, only a few molecules from  PRASHANT KIRAD a given amount undergo partial dissociation in water, producing their respective ions (H+(aq) for acids and OH−(aq) for bases). Dilute acid: contains less number of H+(aq) ions per unit volume. Concentrated acid: contains more number of H+(aq) ions per unit volume. Q. What is a universal indicator? A universal indicator is a mixture of several pH indicators that shows a gradual color change over a wide range of pH values (typically from pH 1 to 14), allowing it to determine the acidity or alkalinity of a “pH scale topic is solution. It provides a different color for each pH important” value, making it useful for estimating the pH of a - Prashant Bhaiya solution more accurately than using a single indicator. pH Scale: D The pH scale, developed for measuring hydrogen ion concentration in a solution, RA derives the "p" from the German term 'potenz,' meaning power. On the pH scale, readings range generally from 0 (indicating strong acidity) to 14 KI (indicating strong alkalinity). pH is a numerical representation of the acidic or basic nature of a solution. T A lower pH value corresponds to a higher concentration of hydrogen ions. A neutral solution has a pH of 7. AN Values below 7 on the pH scale represent an acidic solution. As the pH value increases from 7 to 14, it signifies a rise in the concentration of H OH− ions, indicating an increase in the strength of the alkali. The pH scale is often measured using paper impregnated with a universal indicator. AS PR Importance of pH in everyday life: Our body works within the pH range of 7.0 to 7.8. When pH of rainwater is less than 5.6, it is called acid rain. When acid rain flows into the rivers, it lowers the pH of the river water. The survival of aquatic life in such rivers becomes difficult.  PRASHANT KIRAD pH in our digestive system: It's fascinating to observe that our stomach naturally produces hydrochloric acid, aiding in the digestion of food without causing harm to the stomach lining. However, in instances of indigestion, an excess of stomach acid can lead to discomfort and irritation. To alleviate this pain, individuals often turn to bases known as antacids. These antacids work by neutralizing the surplus acid. Magnesium hydroxide, commonly known as Milk of Magnesia, is a mild base frequently employed for this purpose. pH change as the cause of tooth decay: Tooth decay starts when the pH of the mouth is lower than 5.5. Tooth enamel, made up of calcium hydroxyapatite (a crystalline form of calcium phosphate) is the hardest substance in the body. Bacteria present in the mouth produce acids by degradation of D sugar and food particles remaining in the mouth after eating. The best way to prevent this is to clean the mouth after eating RA food. Using toothpaste, which is generally basic, for cleaning the teeth KI can neutralize the excess acid and prevent tooth decay. Self-defense by animals and plants through chemical warfare: T Bee-sting leaves an acid that causes pain and irritation. The use of a mild base like AN baking soda on the stung area gives relief. Stinging hair of nettle leaves injects methanoic acid causing burning pain. H Manufacture of Acids and Bases AS a) Nonmetal oxide + water → acid SO2(g) + H2O(l) → H2SO3(aq) PR SO3(g) + H2O(l) → H2SO4(aq) Non-metal oxides are thus JOSH METER? referred to as acid anhydrides. b) Metal + water → base or alkali + hydrogen Zn(s) + H2O(steam) → ZnO(s)+ H2(g) c) Hydrogen + halogen → acid H2(g) + Cl2(g) → 2HCl(g) d) Few metallic oxides + water → alkali HCl(g) + H2O(l) → HCl(aq) Na2O(s) + H2O(l) → 2NaOH(aq) e) Ammonia + water → ammonium hydroxide NH3(g) + H2O(l) → NH4OH(aq) f) Metallic salt + conc. sulphuric acid → salt + more volatile acid 2NaCl(aq) + H2SO4(aq) → Na2SO4(aq) + 2HCl(aq) 2KNO3(aq) + H2SO4(aq) → K2SO4(aq) + 2HNO3(aq)  PRASHANT KIRAD EMA Salts Salt is formed through the combination of an anion derived from an acid and a cation derived from a base. Examples of salts include KCl, NaNO3, CaSO4, and others. Typically, salts are produced through the neutralization reaction between an acid and a base. Commonly known as common salt, Sodium Chloride (NaCl) is extensively utilized globally in cooking. Salts sharing the same cation or anion are considered part of the same salt family. Examples include NaCl, KCl, LiCl. pH of Salts: Salts of a strong acid and a strong base are neutral with a pH value of 7. Salts of a strong acid and weak base are acidic with a pH value of less than 7. Those of a strong base and weak acid are basic in nature with a pH value of more than 7. D Chemicals From Common Salt RA The salt formed by the combination of hydrochloric acid and sodium hydroxide solution is called sodium chloride (NaCl)/Common Salt. The common salt thus obtained is an important raw material for various materials of KI daily use, such as sodium hydroxide, baking soda, washing soda, bleaching powder, and many more. T Sodium hydroxide or lye or caustic soda AN Baking soda or sodium hydrogen carbonate, or sodium bicarbonate Washing soda or sodium carbonate decahydrate Bleaching powder or calcium hypochlorite H AS 1.Sodium Hydroxide When electricity is passed through salty water (brine), it breaks down to make sodium hydroxide. This process is called the chlor-alkali process because it produces chlorine PR and alkali (sodium hydroxide). 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + Cl2 (g) + H2 (g) At one end (anode), chlorine gas is released, and at the other end (cathode), hydrogen gas is given off. Close to the cathode, we get a solution of sodium hydroxide.  PRASHANT KIRAD 2.Bleaching Powder Chlorine gas is utilized in the manufacturing process of bleaching powder. The production of bleaching powder involves the interaction of chlorine with dry slaked lime [Ca(OH)2]. While bleaching powder is often represented as CaOCl2, its actual composition is more complex. Ca(OH)2 + Cl2 → CaOCl2 + H2O. Bleaching powder is used – for bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories, and for bleaching washed clothes in laundry; as an oxidizing agent in many chemical industries; and to make drinking water free from germs. 3.Baking Soda Sodium bicarbonate, commonly known as baking soda or bicarbonate of soda, has the chemical formula NaHCO3 and is recognized by the IUPAC name sodium hydrogen D carbonate. This salt is created by the combination of a RA sodium cation (Na+) and a bicarbonate anion (HCO3). Found as a fine powder, sodium bicarbonate is a white, crystalline substance. Its taste is mildly salty and KI alkaline, resembling that of washing soda (sodium carbonate). T AN Chemical name – Sodium hydrogen carbonate Chemical formula – NaHCO3 H 4.Water of Crystallization AS The water of crystallization is the fixed number of water molecules present in one formula unit of salt. Five water molecules are present in one formula unit of copper sulphate. The chemical formula for hydrated copper sulphate is CuSO4.5H2O. PR 5.Plaster of Paris On heating gypsum (CaSO4.2H2O) at 373 K, it loses water molecules and becomes calcium sulphate hemihydrate (CaSO4.1/2H2O). This is called Plaster of Paris. Uses of Plaster of Paris: It is employed by medical professionals to create casts for maintaining fractured bones in the correct position. In the realm of creativity, Plaster of Paris is utilized for crafting toys, decorative items, and achieving smooth surfaces.  PRASHANT KIRAD Important activities D Take a few zinc granules in a boiling tube and add approximately 5 mL of dilute RA sulphuric acid to it. Observe the formation of gas bubbles on the surface of the zinc granules. Direct the gas being produced through a soap solution in a trough using a glass delivery KI tube. This results in the formation of gas-filled bubbles in the soap solution that rise into the air. T Bring a burning candle close to a gas-filled soap bubble. The gas within the soap AN bubble ignites with a 'pop' sound, indicating a small explosion. This demonstration confirms that only hydrogen gas, which has the characteristic 'pop' sound when ignited, is evolved in the reaction between dilute sulphuric acid H and zinc metal (present in the form of zinc granules). AS PR Take a boiling tube and place approximately 0.5 g of sodium carbonate in it. Add about 2 mL of dilute hydrochloric acid to the boiling tube using a thistle funnel. Observe the brisk effervescence of a gas being produced. Pass the gas generated through lime water. Notice that the lime water turns milky, indicating the presence of carbon dioxide gas. Continue passing carbon dioxide gas through the milky lime water for some time. Eventually, the lime water becomes clear again.  PRASHANT KIRAD This demonstrates that the initially formed white precipitate of calcium carbonate dissolves when excess carbon dioxide gas is passed. Repeat the experiment using sodium hydrogen carbonate instead of sodium carbonate. Again, carbon dioxide gas is produced, turning the lime water milky. Upon passing an excess of carbon dioxide, the milky lime water once again becomes clear. D RA KI Place 1 g of solid sodium chloride (NaCl) in a clean, dry boiling tube. T Carefully add concentrated sulfuric acid, fitting the rubber cone over the glass AN tube. The reaction forms hydrogen chloride gas, observed escaping from the open end. Test the gas with a 'dry' blue litmus paper, noting no change in color, indicating HCl H gas doesn't act as an acid in the absence of water. AS Test the gas with a 'moist' blue litmus paper, observing a color change to red, revealing acidic behavior of HCl gas in the presence of water. Conclusion: HCl gas is not acidic in the absence of water but displays acidic PR behavior in the presence of water.  PRASHANT KIRAD # TOP 7 IMPORTANT QUESTIONS 1) A dry pellet of a common base B absorbs moisture and turns sticky when kept open. The compound is also a by-product of the chlor-alkali process. Identify B. What type of reaction occurs when B is treated with an acidic oxide? Write a balanced chemical equation for one such solution. Solution: Sodium hydroxide (NaOH) is a commonly used base and is hygroscopic; it absorbs moisture from the atmosphere and becomes sticky. A neutralization reaction occurs when acidic oxides react with the base to give salt and water. D 2 NaOH + CO2 → Na2CO3 + H2O 2) Give reasons for the following: RA (i) Only one-half of the water molecule is shown in the formula of the plaster of Paris. KI (ii) Sodium hydrogen carbonate is used as an antacid. (iii) On strong heating, blue-colored copper sulfate crystals turn white. (2020) T AN Solution: (i) Only one-half of the water molecule is shown in the formula of plaster of Paris H (CaSO4. 1/2H2O) as one molecule of water is being shared by two molecules of calcium AS sulphate (CaSO4). So the effective water of crystallization for one CaSO4 unit comes to half a molecule of water. (ii) Acidity can be neutralized by a base. Sodium hydrogen carbonate can be used as an PR antacid solution because it is a weak base and will react with excess acid produced in the stomach due to hyperacidity and will neutralize it. (iii) Blue colored copper sulphate crystals are hydrated copper sulphate, CuSO4.5H2O. On heating blue copper sulphate crystals lose their water of crystallization and turn into anhydrous copper sulphate which is white. Heat CuSO4. 5H2O → CuSO4 + 5H2O (Blue) (White) 3) A white powder is added while baking cakes to make them soft and spongy. Name its main ingredients. Explain the function of each ingredient. Write the chemical reaction taking place when the powder is heated during baking. (AI2019) Solution: The white powder added while baking cakes to make them soft and spongy is baking  PRASHANT KIRAD powder. Its main ingredients are sodium hydrogen carbonate and a mild edible acid like tartaric acid or citric acid. NaHCO3 decomposes to give out CO2 which causes the cake to rise and makes it soft and spongy. The function of tartaric acid or citric acid is to neutralize sodium carbonate formed during heating which can otherwise make the cake bitter. The reaction taking place when the powder is heated: Heat 2NaHCO3 → Na2CO3 + H2O + CO2 4) The pH of a salt used to make tasty and crispy pakoras is 14. Identify the salt and write a chemical equation for its formation. List its two uses. (2018) Solution: Salt used to make tasty and crispy pakoras is sodium bicarbonate (NaHCO3), pH = 9. On a large scale, sodium bicarbonate is prepared as: NaCl + H2O + CO2 + NH3 → NH4Cl + NaHCO3 D (Sodium Chloride) (Water) (Carbon Dioxide) (Ammonia) (Ammonium Chloride) (Sodium Bicarbonate) RA 5) A white-colored powder is used by doctors to support fractured bones. KI (a)Write the chemical name and formula of the powder. (b)When this white powder is mixed with water a hard solid mass is obtained. Write T the balanced chemical equation for this change. (Board Term I, 2016) AN Solution: H AS (a) Chemical name of the powder is calcium sulphate hemihydrate. The chemical formula of the powder is CaSO4.1/2H2O. (b) When water is added to the plaster of Paris, it sets into a hard mass in about half an PR hour. The setting of the plaster of Paris is due to its hydration to form crystals of gypsum which set to form a hard, solid mass. 1 1 CaSO4. H2O + 1 H2O → CaSO4. 2H2O 2 2 (Plaster of Paris) (Water) Gypsum (Sets as Hard mass) 6) 6) List the important products of the Chlor-alkali process. Write one important use of each. (2020) Solution: Sodium hydroxide is prepared by electrolysis of an aqueous solution of sodium chloride (brine). The complete reaction can be represented as: The process of electrolysis of sodium chloride solution is called chlor-alkali process because of the products formed : chlor for chlorine and alkali for sodium hydroxide. The three very useful products obtained by the electrolysis of sodium chloride solution are sodium hydroxide, chlorine and hydrogen.  PRASHANT KIRAD On passing 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + H2 (g) + Cl2 (g) Electricity At anode: Cl2 gas is liberated and at cathode: H2 gas is liberated. Uses of sodium hydroxide: In the manufacture of soaps and detergents. Uses of chlorine: As a germicide and disinfectant for sterilization of drinking water and for water of swimming pools. Uses of hydrogen: In the manufacture of ammonia which is used for the preparation of various fertilizers like urea, ammonium sulphate, etc. 7) How is washing soda prepared from sodium carbonate? Give its chemical equation. State the type of this salt. Name the type of hardness of water which can be removed by it. (2020) Solution: Washing soda is prepared by recrystallization of sodium carbonate: D NA2CO3 (s) + 10H2O (l) → NA2CO3. 10H2O (s) RA Anhydrous Washing Soda Sodium Carbonate KI It is used to remove the permanent hardness of water. Hard water is treated with a calculated amount of washing soda when chlorides and sulfates of calcium and magnesium T present in hard water get precipitated as insoluble calcium and magnesium carbonates AN which can be easily filtered off. The water thus becomes soft. H CaCl2 + Na2CO3 → CaCO3↓ + 2NaCl AS MgSO4 + Na2CO3 → MgCO3↓ + Na2SO4 PR “Class 10th Phodenge”  CLASS 10 NOTES SCIENCE Metals and Non Metals PRASHANT KIRAD  PRASHANT KIRAD Metals Those elements which form ions by losing electrons are called metals. Physical properties of metals LUSTRE MALLEABILITY CONDUCTIVITY HIGH MP AND BP DENSITY SOLID STATE DUCTILITY SONOROUS “Bahut Jaroori Table” - Prashant Bhaiya Properties Description/Defination Metals have a shiny appearance, known as metallic lustre, which is due Lustre to the reflection of light from their surface. Metals can be hammered or rolled into thin sheets without breaking. Malleability This property is known as malleability. Metals are excellent conductor of heat and electricity. Silver and Conductivity copper are particularly good electrical conductors, which is why they are widely used in electrical circuits. Metals can be drawn into thin wires. This property is called ductility. Ductility Copper and aluminum are common examples, often used for electrical wiring. Most metals have high melting and boiling points due to the strong High Melting and bonding between their atoms. For example, iron and tungsten have very Boiling Points high melting points. Most metals are solid at room temperature, with the exception of Solid State mercury, which is liquid. Metals typically have high density, meaning they are heavy for their Density size. Metals produce a ringing sound when struck, a Sonorous property known as sonority. This is why metals like iron and brass are used in making bells and musical instruments.  PRASHANT KIRAD Chemical properties of metals RXN WITH WATER RXN WITH ACIDS RXN WITH SALTS RXN WITH NON METALLIC ELEMENTS RXN WITH OXYGEN Reaction with oxygen: When metals react with oxygen, they form metal oxides. Most metal oxides are basic in nature, meaning they can react with acids to form salt and water. Metals + Oxygen → Metal Oxide VIP (very import ant portion) Potassium and sodium metals are extremely reactive, undergoing vigorous reactions with the oxygen in the air. In the presence of air, they can readily catch fire and burn. To prevent these reactive metals from reacting with oxygen, moisture, and carbon dioxide in the air, they are stored in kerosene oil. This protective measure ensures that the metals remain stable and do not undergo combustion when exposed to atmospheric conditions. Reaction with Water: Metals react with water to form metal hydroxides and hydrogen gas. The reactivity with water varies among metals: Highly reactive metals (like sodium and potassium) react vigorously with cold water. Less reactive metals (like magnesium) react with hot water. Least reactive metals (like iron) react with steam. Metals + Water → Metal Hydroxide + Hydrogen JOSH METER? Reaction with Acids: Metals react with dilute acids to produce salt and hydrogen gas. This reaction is more vigorous with more reactive metals. Metals + Acid → Salt + Hydrogen Displacement Reaction: A more reactive metal can displace a less reactive metal from its compound in solution. This is known as a displacement reaction. Example: CuSO4 + Zn → ZnSO4 + Cu Reaction with Non-metals: Metals can react with non-metals to form ionic compounds, where metals lose electrons to form cations and non-metals gain electrons to form anions. Example: 2 Na + Cl2 → 2 NaCl2  PRASHANT KIRAD Explanation: In this activity, metal samples are placed in cold water to observe reactions. Reactive metals are arranged by increasing reactivity. Fire and floating observations are noted. Non-reactive metals with cold water are tested in hot water and steam. The final arrangement is based on decreasing reactivity with water, considering reactions with hot water and steam. Reactivity series of Metals: The reactivity series of metals is a list that ranks metals from most reactive to least reactive. This series is useful for predicting how metals will react with water, acids, and other substances, as well as in displacement reactions. EMA Non-Metals Those elements which form negative ions by gaining electrons are called non-metals. Physical properties of Non-metals: Lack of luster: Non-metals are generally not shiny. Brittleness: Non-metals are brittle and break easily when hammered. Poor conductivity of heat and electricity: Non-metals do not conduct heat and electricity well, except for graphite, which is a good conductor of electricity. Low Melting and Boiling point: Non-metals generally have lower melting and boiling points than metals. Low Density: Non-metals usually have lower densities compared to metals.  PRASHANT KIRAD Chemical properties of Non-metals: Combustibility: Some non-metals, like hydrogen and carbon, can undergo combustion reactions. Reaction with Oxygen: Non-metals may react with oxygen to form oxides. For example, sulfur reacts with oxygen to form sulfur dioxide. Acid-Base Reactions: Non-metals can react with bases to form salts. For instance, sulfuric acid, a non-metal compound, reacts with sodium hydroxide to form sodium sulfate and water. Hydrogen Ion Formation: Non-metals may accept electrons to form negatively charged ions (anions) in reactions with metals. Covalent Bonding: Non-metals form covalent bonds by sharing electrons with non-metals. Reaction with Water: Some non-metals, such as sulfur and phosphorus, react with water to produce acids. Reaction with Metals: Non-metals can displace less reactive metals from their salts in solution, forming new compounds. Metals and Non-Metals When metals interact with non metals, they combine to create ionic compounds. Conversely, when nonmetals engage with other nonmetals, they form covalent compounds. Ionic compounds: Ionic compounds are chemical compounds composed of positively charged ions (cations), usually derived from metals, and negatively charged ions (anions), usually derived from nonmetals. Formation: Ionic compounds are formed by transferring electrons from the metal atom to the nonmetal atom. This transfer results in the formation of ions with opposite charges. Ionic Bonding: Ionic bonding is the electrostatic attraction between positively charged ions (cations) and negatively charged ions (anions). This attraction holds the ions together in a stable compound. Properties: 1. Ionic compounds generally have high melting and boiling points. 2. They are usually solid at room temperature. 3. They conduct electricity when dissolved in water or melted, as ions are free to move. Examples: Common examples of ionic compounds include sodium chloride (NaCl), potassium iodide (KI), and magnesium oxide (MgO). Properties of Ionic Compounds: High Melting and Boiling Points: Ionic compounds typically have high melting and boiling points due to strong electrostatic forces holding ions together in three- dimensional lattice. Solubility in Water: Many ionic compounds are soluble in water because water molecules surround and separate the ions, facilitating their movement.  PRASHANT KIRAD Conductivity: Ionic compounds conduct electricity when dissolved in water or molten, as ions become free to move and carry an electric charge. Brittleness: Solid ionic compounds are often brittle because when force is applied, layers of ions with like charges align, leading to repulsion and cleavage. Occurrence of Metals Metals are predominantly obtained from the Earth's crust, which serves as a major reservoir for these elements. Seawater contains soluble salts like sodium chloride and magnesium chloride. The naturally occurring elements or compounds found in the Earth's crust are referred to as minerals. Minerals that can be profitably processed to extract metals are specifically termed ores. Extraction of metals from ores Metallurgy: Metallurgy is the science and process of extracting metals from their ores, refining them, and preparing them for use. Metal extraction methods vary depending on the position of metals in the activity series: Highly Reactive Metals: Metals with high reactivity, such as Potassium (K), Sodium (Na), Calcium (Ca), and Magnesium (Mg), are typically extracted through electrolysis. Their strong bonding with other components prevents reduction by heating with carbon. Moderately Reactive Metals: Moderately reactive metals like Zinc (Zn), Iron (Fe), and Lead (Pb) are generally extracted through reduction processes using agents like coke (C). Less Reactive Metals: Less reactive metals, for instance, Copper (Cu) and Mercury (Hg), are extracted from their oxides through heating alone, a method known as self- reduction. Very Less Reactive Metals: Metals with very low reactivity, such as Silver (Ag), Gold (Au), and Platinum (Pt), exist in nature in the metallic form and do not “Reactivity Series pakka require extraction processes. exam me aayegi” The concentration of ores: - Prashant Bhaiya When metals interact with nonmetals, they combine to create ionic compounds. Conversely, when nonmetals engage with other nonmetals, they form covalent compounds. Gravity Separation: Using the difference in the density of ore and impurities. Froth Flotation: Involves the separation of ore from impurities by using froth formed by certain chemicals. Magnetic Separation: Used when either the ore or the impurities are magnetic.  PRASHANT KIRAD Extraction of Metals of LOW Reactivity: Direct Reduction: Sulfide ores of less electropositive metals like Mercury (Hg), Lead (Pb), and Copper (Cu) undergo self-reduction when heated in air. No external reducing agent is used in this process. Cinnabar (HgS): 2HgS (Cinnabar) + 302 (g) + heat → 2HgO (crude-metal) + 2SO2 (g) : 2HgO (s) + heat → 2Hg (1) + O2 (g) Copper Glance (Cu2S): Cu2S (Copper-pyrite) + 302 (g) + heat → 2Cu2O (s) + 2SO2 (g) : 2Cu2O(s) + Cu2S (s) + heat → 6Cu (crude metal) + SO2 (g) Galena (PbS): 2PbS (Galena) + 302 (g) + heat → 2PbO (s) + 2SO2 (g) : PbS (s) + 2PbO (s) → 2Pb (crude metal) + SO2 (g) Extraction of Metals of MEDIUM Reactivity: These metals are usually preset as sulphides or carbonates in nature. The extraction of metals of medium reactivity, such as iron, zinc, and lead, typically involves the following steps: These sulphides or carbonates are first converted into oxides because it is easy to extract metals from its oxides. Sulphides are converted into oxides by roasting and carbonates are converted into oxides by calcination. Roasting: Roasting involves heating of ore lower than its melting point in the presence of air or oxygen. Example of Zinc Sulphide ore: 2ZnS (s) + 3O2 (s) → 2ZnO (s) + 2SO2 (g) Calcination: Calcination involves thermal decomposition of carbonate ores. Example of Zinc carbonate ore: ZnCO3 (s)​→ ZnO (s) + CO2 (g)​ The metal oxides thus obtained are then reduced to the corresponding metals by reduction process. Depending upon the reactivity of metals, reduction is done in different ways as: Smelting (Reduction with Carbon): This process, the roasted or calcined ore is mixed with suitable quantity of coke or charcoal (which act as reducing agent) and is heated to a high temperature above its melting point. Example of Zinc: ZnO (s) + C (s) → Zn (s) + CO (g) Thermite process: It is the technique, to reduce metal oxide using more reactive metal powder as fuel. Aluminium, magnesium, titanium are some metals which are used as fuel in thermite process. In this process, a mixture of concentrated oxide ore and metal powder (i.e., thermite) is taken in a steel crucible and kept on sand. A mixture of magnesium powder and barium peroxide (called ignition mixture) is used to ignite the reaction mixture. A large amount of heat is evolved during the reaction which melts the metal.  PRASHANT KIRAD Example: Cr2​O3 (s) ​+ 2Al (s) → 2Cr(l) + Al2​O3 (s)​ : Fe2​O3 (s)​+ 2Al (s) → 2Fe (l) + Al2​O3 (s) {Gold-Schmidt aluminothermic reduction}​ Electrolytic Reduction: Highly reactive metals like Na, K, Mg, Ca, Al, etc, are reduced by electrolysis of their respective oxides, hydroxides of chloride in molten state. On passing electric current into the molten solution, metal is liberated at cathode while impurities are settled down as anode mud generally. Example: NaCl → Na+ (l) + CL- (s)​ At cathode: Na+ + e− → Na At anode: 2Cl− → Cl2 ​+ 2e− Refining/Purification of Metal: The reduced metals obtained are generally impure which may be associated with following types of impurities as - Uncharged (not reduce associated with following types of ore. Other metals that are produced by simultaneous reduction of their compounds originally present in the ore Non-metals like silicon, carbon, phosphorous etc. Slag, flux etc., which is present in residual condition. These impurities can be removed by "refining of metals". These Impurities are removed by "refining of metals" as: JOSH METER? Electrolytic Refining (Purification of copper): In this process, a thick block of impure metal is used as anode and a thin strip of pure metal is used as cathode. A solution of metal salt (to be refined) is used as an electrolyte. When electric current is passed, metal ions from the electrolyte are reduced as metal which get deposited on the cathode. An equivalent amount of pure metal from the anode gets oxidized to metal ion and goes into the electrolyte and from there it goes to cathode and deposit. Cu (impure)​→Cu (pure) ​+ impurities At cathode: Cu2+ + 2e− → Cu (pure)​ At anode: Cu (impure) ​→ Cu2+ + 2e− Corrosion Corrosion refers to the gradual deterioration of a material, typically a metal, due to the influence of moisture, air, or chemicals in the surrounding environment. An example is the rusting of iron.  PRASHANT KIRAD # TOP 7 IMPORTANT QUESTIONS 1) Explain why calcium metal after reacting with water starts floating on its surface. Write the chemical equation for the reaction. Name one more metal that starts floating after some time when immersed in water. Solution: When calcium metal reacts with water, it produces hydrogen gas and calcium hydroxide. The hydrogen gas bubbles stick to the surface of the calcium, creating buoyancy, causing calcium to float on the water's surface. The chemical equation for the reaction is: Ca (s) + 2H2O (l) → Ca(OH)2 (aq) + H2 (g) Another metal that starts floating after some time when immersed in water is sodium. 2) (a) (i) Write two properties of gold that make it the most suitable metal for ornaments. (ii) Name two metals which are the best conductors of heat. (iii) Name two metals that melt when you keep them on your palm. (iv) Explain the formation of the ionic compound CaO with an electron-dot structure. Atomic numbers of calcium and oxygen are 20 and 8 respectively. [5M, 2020] Solution: (i). The property of gold used in making ornaments is ductility and luster. (ii). Silver are copper are the best conductors of heat. (iii). Gallium and cesium are the metals that melt when kept on the palm. (iv) Atomic no. of Ca - 20, Electronic Configuration 2,8,8,2. Atomic no. of O - 8 Electronic Configuration - 2,6 3) (a)Carbon cannot be used as a reducing agent to obtain Mg from MgO. Why? (b) How is sodium obtained from molten sodium chloride? Give an equation of the reactions. (c) How is copper obtained from its sulfide ore? Give equations of the reactions. Solution: (a) Carbon and MgO: - Carbon can't reduce MgO; Mg is more reactive. (b) Sodium from Molten NaCl: -Na obtained from molten NaCl by electrolysis: 2NaCl (l) 2Na (l)+Cl2(g)  PRASHANT KIRAD (c) Copper from Sulfide Ore: - Copper from CuFeS2 by smelting: CuFeS2(s) + O2(g)→Cu (l)+FeO (s)+SO2(g) 4) The way, metals like sodium, magnesium, and iron react with air and water is an indication of their relative positions in the 'reactivity series'. Is this statement true? Justify your answer with examples. Solution: Yes, the statement is true. The reactivity series ranks metals based on their tendency to undergo reactions. Metals like sodium, which reacts vigorously with both air and water, magnesium, which burns in air and reacts with water, and iron, which reacts with oxygen and steam, demonstrate the correlation between their reactivity and their positions in the reactivity series. 5) A non-metal X exists in two different forms, Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y, and Z. Solution: X is carbon. Diamond and graphite are allotropes of carbon. Diamond is the hardest natural substance, and hence Y is diamond. Graphite is a good conductor of electricity, and hence Z is graphite. 6) What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires? Solution: Constituents of Solder Alloy: - Typically, tin and lead or lead-free alternatives with elements like silver, copper, or antimony. Property Suitable for Welding Electrical Wires: - Low melting point of solder (below 450°F or 232°C), enabling easy melting and secure bonding without damaging the electrical wires. 7) A metal that exists as a liquid at room temperature is obtained by heating its sulfide in the presence of air. Identify the metal and its ore and give the reaction involved. Solution: Mercury is the only metal that exists as a liquid at room temperature. It can be obtained by heating cinnabar (HgS), the sulfide ore of mercury. We can get metals low in activity series by heating or reducing their sulfides or oxides. The reactions are as follows: 2 HgS + 3 O2 → 2 HgO + 2 SO2 2 HgO → 2 Hg + O2 “Class 10th Phodenge” - Prashant Bhaiya  CLASS 10 NOTES SCIENCE Carbon and It’s Compound PRASHANT KIRAD  PRASHANT KIRAD Atomic Number of Carbon 6 Carbon achieves stability with 4 electrons in its outermost shell. While it could gain four electrons to form a carbon anion, removing electrons poses challenges due to the substantial energy requirement. Gaining or losing electrons influences the formation of bonds in chemical compounds. To solve this issue, carbon shares its outer electrons with other carbon or different atoms. This sharing helps both atoms reach a stable configuration, similar to noble gases. This sharing is called covalent bonding. D RA Examples of Covalent Bonding: KI Formation of Hydrogen Molecule: The hydrogen molecule (H 2 ) forms when two hydrogen atoms come close together. T Each hydrogen atom shares its electron with the other, creating a covalent bond. AN This sharing completes their outer electron shells, making the molecule stable. The chemical equation for this process is H + H → H 2 H AS PR Formation of chlorine Molecule (Cl 2): Chlorine gas (Cl 2) forms when two chlorine atoms combine. Each chlorine atom contributes one electron, creating a covalent bond. This shared electron pair satisfies the octet rule, making the molecule stable. The chemical equation Formation of Oxygen Molecule (O2 ): Two oxygen atoms combine to form an oxygen molecule (O2). The chemical equation is 2O → O2 showing that two oxygen atoms come together to create one oxygen molecule.  PRASHANT KIRAD Formation of Nitrogen Molecule (N 2): Two nitrogen atoms combine to form a nitrogen molecule (N2 ). The chemical equation is N + N → N2 indicating that two nitrogen atoms come together to create one nitrogen molecule. D RA Formation of Methane (CH 4): Methane CH 4 forms when one carbon atom combines with four hydrogen atoms. The KI chemical equation for this is C + 4H2→ CH 4 indicating the combination of carbon and hydrogen to produce methane. T AN H AS PR Methane, or marsh gas, is a vital fuel used in CNG and Biogas. It not only serves as a potent energy source but also participates in reactions forming essential compounds like (Ammonia NH 3 ),(Water H 2 O), and (Carbon Dioxide CO2) This versatility underscores its significance in both energy and environmental contexts. Formation of Sulphur (S 8 ):  PRASHANT KIRAD Properties of covalent Bond: EMA Low Melting and Boiling Points: Covalent compounds have low melting and boiling points due to weak intermolecular forces. Weak Intermolecular Forces: Covalent compounds exhibit weak forces between molecules. Electron Sharing Between Atoms: Electrons are shared between atoms in covalent bonds. No Charged Particles Formed: Covalent compounds do not form charged particles; electrons are shared, not transferred. Allotropes of carbon: EMA Allotropy is the characteristic of an element to exist in multiple forms, where each form possesses distinct physical properties while maintaining identical chemical properties. D RA DIAMOND: Properties: KI Very Hard Does not conduct Electricity T Transparent and colorless. AN Uses: Industrial cutting tools due to hardness. Jewelry and gemstones. H AS GRAPHITE: Properties: PR Conductivity: Excellent electrical conductivity. Thickness: Single layer of carbon atoms arranged in a hexagonal lattice. Strength: Exceptionally strong. Uses: Lubricants and as a dry lubricant in locks and mechanisms. Electrodes in batteries. Pencils (as pencil lead). Moderators in nuclear reactors. FULERENES: The fullerene C60 was named "Buckminsterfullerene" after Buckminster Fuller. The initial discovered fullerene is C60, also known as Buckminsterfullerene, and it comprises 60 carbon atoms.  PRASHANT KIRAD Versatile Nature of carbon: EMA The versatile nature of carbon is attributed to its ability to form a wide variety of compounds, owing to the following characteristics: Tetravalency: Carbon can form four covalent bonds, allowing it to bond with various other atoms, including itself, to create diverse molecular structures. Catenation: Carbon exhibits a high degree of catenation, meaning it can form long chains, branched structures, or rings, contributing to the diversity of carbon-based molecules. Allotropy: Carbon exists in different allotropes, such as diamond, graphite, graphene, fullerenes, and carbon nanotubes, each with distinct properties and applications. Isomerism: Carbon compounds can have different structural or spatial arrangements, leading to the existence of isomers—molecules with the same molecular formula but different structures. D Polymerization: Carbon is integral to the formation of polymers, enabling the RA creation of a wide range of synthetic materials with diverse applications. These characteristics collectively contribute to carbon's versatility, making it a KI cornerstone of organic chemistry and a crucial element for the existence of life as we know it. T AN HYDROCARBONS H AS SATURATED UNSATURATED PR Compounds of carbon are It is the electric current which reverses linked only by single bonds its direction after every fixed interval of between the carbon atoms. time. -Type of Saturated -Types of Unsaturated Hydrocarbons: Hydrocarbon: Alkanes Alkenes and Alkynes ALKANES: - Hydrocarbons with all carbon atoms linked by single covalent bonds are alkanes or paraffins. - General formula: CnH2n+2. ALKENES: - Unsaturated hydrocarbons with at least one double bond along with single bonds are called alkenes or olefins.  PRASHANT KIRAD - General formula: CnH₂n where n>2 - ALKYNES: - Unsaturated hydrocarbons with one or more triple bonds along with single bonds are alkynes. - General formula: CnH2n−2 Note: For alkenes, n must be greater than 2, and for alkynes, n must be greater than or equal to 2 to ensure a minimum number of carbon atoms for a double or triple bond. IUPAC Nomenclature of Hydrocarbons: IUPAC (International Union of Pure and Applied Chemistry) nomenclature is a systematic method used to name organic D compounds, including hydrocarbons. RA KI T AN Most important Topic - Nomenclature” H - Prashant Bhaiya AS PR Alkanes (Saturated Hydrocarbons): - End the name with "-ane." - Number the carbon atoms in the longest continuous chain. - Identify and name any substituents (side branches). - Combine the names of the substituents with the chain name. - Example: CH3CH2CH2CH3 is butane. Alkenes (Unsaturated Hydrocarbons with Double Bonds): - End the name with "-ene." - Number the carbon atoms in the longest continuous chain. -Identify the location of the double bond and include it in the name. - Example: CH2=CH−CH3 is propene.  PRASHANT KIRAD Alkynes (Unsaturated Hydrocarbons with Triple Bonds): End the name with "-yne." - Number the carbon atoms in the longest continuous chain. - Identify the location of the triple bond and include it in the name. - Example: CH≡C−CH2−CH3 is propyne. Remember to follow the IUPAC rules for numbering and prioritizing substituents. The goal is to provide a systematic and unique name for each hydrocarbon based on its structure. Steps for writing IUPAC Names: 1. Identify the Longest Carbon Chain: - Locate the longest continuous chain of carbon atoms in the molecule. 2. Number the Carbon Chain: D - Number the carbon atoms in the chain from the end that gives RA substituents the lowest numbers. 3. Identify and Name Substituents: KI - Identify and name any substituents (groups attached to the main carbon chain). 4. Combine Chain and Substituent Names: T - Combine the names of the main carbon chain and substituents, alphabetizing them. AN 5. Add Prefixes and Suffixes: - Add prefixes and suffixes based on the type of compound (alkane, H alkene, alkyne). AS Examples: PR 4. CH₃CH₂CH₂COOH: 1. CH₃CH₂CH₂CH₂CH₃: Longest Chain: 4 carbon Longest Chain: 5 carbon atoms (Pentane). atoms (Butane). IUPAC Name: Pentane. Substituent: COOH (Carboxyl group at the 1st carbon). 2. CH₃CH₂CH₂OH: IUPAC Name: Butanoic acid. Longest Chain: 3 carbon atoms (Propane). Substituent: OH (Hydroxy group at the 1st carbon). IUPAC Name: Propan-1-ol (or simply Propanol). 3. CH₂=CHCH₃: Longest Chain: 3 carbon atoms (Propene). IUPAC Name: Propene.  PRASHANT KIRAD Drawing Structures of Saturated and Unsaturated Compounds: Connect All Carbon Atoms with Single Bonds: - Use single bonds to link all carbon atoms together in the molecule. Satisfy Remaining Valencies of Carbon with Hydrogen Atoms: - Attach hydrogen atoms to each carbon atom to fulfill their valency. - Carbon typically forms 4 bonds due to its 4 valencies. If Available Hydrogen Atoms are Insufficient: - If the number of available hydrogen atoms is less than required, use double or triple bonds to satisfy the remaining valency of carbon. 1.The structural formula for propane is: D RA KI T AN This represents a straight-chain alkane with three carbon atoms, each bonded to two hydrogen atoms. The carbon atoms are connected by single bonds. H 2. The structural formula for ethene (also known as ethylene) is: AS PR This represents an alkene with two carbon atoms and a double bond between them. Each carbon atom is bonded to two hydrogen atoms. 3. The structural formula for propyne is:  PRASHANT KIRAD This represents an alkyne with the carbon atoms. The triple bond is between the first and second carbon atoms. Each carbon atom is bonded to one hydrogen atom. 4. The structural formula for cyclohexane is represented as a hexagon: Cyclohexane is a cyclic alkane with six carbon atoms forming a ring, and each carbon is bonded to two hydrogen atoms. The bond angles in the ring are approximately 109.5 degrees, creating a stable and symmetrical structure. D 5. The structural formula for benzene is represented as a hexagon with a circle inside: RA KI T AN H AS This representation indicates that benzene has a stable and symmetrical ring structure with six carbon atoms. The circle inside the hexagon signifies the PR delocalized pi electrons, highlighting the resonance structure of benzene. Each carbon atom is bonded to one hydrogen atom, and all carbon-carbon bonds in benzene are equivalent. Functional Groups: EMA A functional group is an atom or group of atoms within a carbon compound that imparts reactivity and determines its chemical properties. When a compound contains a functional group, it is denoted in the compound's name through the use of either a JOSH METER? prefix or a suffix.  PRASHANT KIRAD Prefix = Chloro/Bromo Suffix -ol Suffix -al Suffix -one Suffix -oic acid D Homologous Series: RA KI A homologous series is a group of organic compounds sharing similar structure and chemical properties, where successive members in the series differ by the T addition of a common CH2 group. For example, CH4, C2H6, and C3H8 AN - All members have the same general formula. - Successive members differ by a CH2 group. - Two adjacent members differ by molecular masses of CH2. H - All members exhibit similar chemical properties (though not necessarily AS identical physical properties). PR Structural Isomerism: Structural isomerism refers to compounds sharing the same molecular formula but exhibiting distinct arrangements of atoms or bonds within their structures. Examples: Ethanol: - A liquid compound, soluble in water. - Commonly referred to as alcohol, it serves as the active ingredient. - Due to its excellent solvent properties, ethanol is employed in various medicines such as tincture iodine, cough syrups, and many tonics.  PRASHANT KIRAD Acetic Acid (C2H4O2): - -- Commonly known as acetic acid. - A 5-8% solution of acetic acid in water is termed vinegar and is used as a preservative in pickles. - With a melting point of 290 K, it tends to freeze during winter. - Carboxylic acids, including acetic acid, are categorized as weak acids. Denatured Alcohol: Denatured alcohol is a form of alcohol that is rendered unsuitable for consumption in large quantities due to its adverse effects on health. Excessive alcohol intake can impede metabolic processes and suppress the central nervous system, leading to issues such as lack of coordination and drowsiness. To prevent the misuse of alcohol, it is intentionally altered by incorporating toxic substances like methanol and pyridine, as well as colored dyes. This modified form of alcohol, known as denatured alcohol, is specifically designed to deter ingestion. D RA Chemical Properties of Carbon Compounds: 1. Combustion: KI Combustion is a chemical reaction that releases heat and light. T Combustion of Carbon: C (s) + O2 (g) → CO2 (g) + Heat + Light AN Combustion of Hydrocarbon: CH4 (g) + O2 (g) → CO2 (g) + H2O (g) + Heat + Light H Combustion of Alcohol: C2H5OH (g) + O2 (g) → CO2 (g) + H2O (g) + Heat + Light AS In each case, the combustion process involves the reaction of the substance with oxygen to produce carbon dioxide (CO2) and water (H2O) accompanied by the release PR of heat and light. Nature of Flame: Saturated hydrocarbons such as methane and ethane burn with a clear blue flame in the presence of sufficient oxygen. Limited oxygen availability for saturated hydrocarbons results in a sooty flame. Unsaturated hydrocarbons like ethene and ethyne burn with a yellow flame and significant black smoke. Kerosene, when burned with sufficient oxygen, produces a clear, blue flame. Some hydrocarbons like benzene and naphthalene burn with a sooty flame. Combusting coal and petroleum primarily yields CO2, CO, nitrogen oxides, and sulfur oxides. The latter contributes to air pollution. 2. Oxidation: Carbon compounds readily undergo oxidation during combustion. 2C (s) + O2 (g) → 2CO (g) (Limited Oxygen, Carbon Monoxide)  PRASHANT KIRAD C(s) + O2(g) → CO2 (g) (Excess Oxygen, Carbon Dioxide) Different amounts of oxygen yield different products. Oxidation of Alcohol: Both alkaline KMnO4 and acidified K2Cr2O7 act as oxidizing agents, supplying oxygen for the oxidation process. 3. Addition Reaction: In the presence of catalysts like palladium or nickel, unsaturated hydrocarbons undergo addition reactions, where hydrogen is incorporated, leading to the formation of saturated hydrocarbons. Catalysts are substances that facilitate a reaction to take place at a different rate, without being consumed in the process. D Hydrogenation Reaction: RA This process is employed in the hydrogenation of vegetable oil. Vegetable oils typically KI consist of long unsaturated carbon chains, whereas animal fats possess saturated carbon chains. Animal fats commonly contain saturated fatty acids, which are detrimental to health. T AN H AS 4. Substitution Reaction: PR A substitution reaction is a chemical process in which one functional group in a chemical compound is exchanged with another functional group. CH3OH + HBr → CH3Br + H2O CH4 + Cl2 → CH3Cl + HCl In these reactions, one functional group is substituted for another, resulting in the formation of new compounds. Reactions of Ethanol: i. Reaction with Sodium: 2Na + 2CH3CH2OH → 2CH3CH2O-Na+ + H2 (sodium ethoxide)  PRASHANT KIRAD ii. Reaction to Form Unsaturated Hydrocarbons: CH3CH2OH → CH2 = CH2 + H2O Hot concentrated H2SO4 acts as a dehydrating agent (which removes water), facilitating the reaction. Reactions of Ethanoic Acid: D RA In these reactions, ethanoic acid participates in esterification, and saponification, and reacts with carbonates and hydrogen carbonates to yield different products. KI Soaps and Detergents: T AN Soaps consist of sodium or potassium salts of long-chain carboxylic acids. The ionic end of the soap dissolves in water, while the carbon chain dissolves in oil. H AS PR Detergents are typically ammonium or sulphorate salts of long-chain carboxylic acids. Cleaning Action of Soap: Most of the dirt is oily, and oil does not dissolve in water. Soap molecules form Structures called micelles. In micelles, one end is oriented towards the oil droplet, while the other, which is ionic, faces Outward. Soap, in the form of a micelle, resides in the center of the micelles. The micelles remain in the solution as a colloid, preventing them from coming together and precipitating due to ion-ion repulsion. Soap micelles are large enough to scatter light; therefore, a soap solution appears cloudy.  PRASHANT KIRAD Hardness of Water: Hard water refers to water with a high mineral content, particularly calcium and magnesium salts. Soap molecules react with these salts, leading to the formation of precipitates, also known as scum. D Soft water, which lacks calcium and magnesium salts, does not form scum with RA soap. Detergents are generally ammonium or sulphonate saltsof long-chain carboxylic KI acids. The charged ends of these compounds do not form insoluble precipitates with hard water, allowing them to remain effective in such conditions. T AN # TOP 7 H AS IMPORTANT QUESTIONS PR 1) A compound X on heating with an excess of cone. H2 SO4 at 443 K gives an unsaturated compound Y. X also reacts with sodium metal to evolve a colorless gas Z. Identify X, Y, and Z. Write the equations of the chemical reaction of formation of Y and also write the role of conc. sulphuric acid in the reaction. [CBSE 2016] Solution:  PRASHANT KIRAD 2) Distinguish between esterification and saponification reactions with the help of equations for each. State one use of each (i) ester (ii) saponification process. Solution: D 3) Explain giving reasons, why carbon can neither form C4+ cation nor C4- anion but forms covalent compounds which are bad conductors of electricity and have low melting and boiling points. [CBSE 2017] RA KI Solution: T Carbon cannot lose four electrons because high energy is needed to remove four AN electrons. It cannot gain 4 electrons because 6 protons cannot hold 10 electrons. It can share 4 electrons to form covalent bonds. Covalent compounds do not conduct electricity because these do not form ions. They have low melting and boiling points due to the weak H force of attraction between molecules. AS 4) Write the chemical equation of the reaction of ethanoic acid with the following: PR a. Sodium b. Sodium hydroxide, c. Ethanol. Write the name of one main product of each reaction. Solution:  PRASHANT KIRAD 5) What is the difference between the molecules of soaps and detergents, chemically? Explain the cleansing action of soap. [CBSE 2015] Solution: Soaps are sodium or potassium salts of fatty acids. They contain the —COONa group. Detergents are sodium or potassium salts of sulphonic acids. They contain —SO3 Na or —SO4 Na group. Soap has an ionic end which is hydrophilic, and interacts with water while the carbon chain is hydrophobic and interacts with oil and grease. The soap molecules orient themselves in a cluster in which hydrophobic tails are inside the cluster and ionic ends face outside. These clusters are called micelles. These attract oil which is washed away by water. 6) Write the molecular formula of the following compounds and draw their electron dot structures: (a) Ethane (b) Ethene