Chemistry Notes - Term 1 PDF

Chem notes for Term 1 Unit 1: Balance ➔ Equilibrium ★ Equilibrium refers to a state where the forward and reverse reactions occur at the same rate, resulting in no net change in the concentration of reactants and products. ★ The symbol “⇌” tells us that the re...

Chem notes for Term 1 Unit 1: Balance ➔ Equilibrium ★ Equilibrium refers to a state where the forward and reverse reactions occur at the same rate, resulting in no net change in the concentration of reactants and products. ★ The symbol “⇌” tells us that the reaction is reversible [meaning the reaction can proceed in either direction (reactants to products OR products to reactants)] ★ In the beginning of the chemical reaction, the forward and backward reaction will take place at different rates ★ In the beginning of a chemical reaction, the forward reaction will be very fast and the backward reaction will be very slow (since it hasn’t started yet) ★ As the reactants turn into products, the forward reaction starts to slow down while the backward reaction picks up the pace/speeds up ★ After a while, the rate of the reactions will even out which results in equilibrium ★ Since the molecules are breaking down and re-forming at the same rate, there will be no overall change in the concentrations ★ The position of equilibrium can change and will shift to the left or right side, depending on the conditions ★ When there are more products, the equilibrium shifts to the right-handed side ★ When there are more reactants, the equilibrium shifts to the left-handed side ★ If heat is added to the reaction, it will encourage the forward reaction, meaning there will relatively be more products as the position of equilibrium moves to the right ★ If we cool the conditions of our reactions however, it would push back the equilibrium back to the left ★ Equilibrium can only be reached if the reversible reaction takes place in a closed system (in which none of the reactants or products can escape) ➔ Writing and Balancing chemical equations ★ Common Polyatomic ions: - Ammonium: NH4+​ - Acetate: C2H3O2− - Bicarbonate (Hydrogen Carbonate): HCO3− - Bisulfate (Hydrogen Sulfate): HSO4− - Carbonate: CO32- - Chromate: CrO42− - Cyanide: CN− - Dichromate: Cr2O72− - Hydroxide: OH− - Nitrate: NO3− - Nitrite: NO2− - Peroxide: O22− - Permanganate: MnO4− - Phosphate: PO43−​ - Sulfate: SO42−​ - Sulfite: SO32−​ - Thiocyanate: SCN−  - Hypochlorite: ClO− - Chlorite: ClO2− - Chlorate: ClO3− - Perchlorate: ClO4− - Hydrogen Phosphate: HPO42− - Dihydrogen Phosphate: H2PO4−​ - Hydrogen Sulfide: HS− - Oxalate: C2O42− ➔ Open, Closed & Isolated Systems ★ Open System: - Definition: An open system can exchange both matter and energy with its surroundings. - Characteristics: Mass can enter or leave the system, Energy can be transferred between the system and its surroundings and Examples include an open flask, a boiling pot of water, and a living organism. ★ Closed System: - Definition: A closed system can exchange energy but not matter with its surroundings. - Characteristics: Mass remains constant within the system, Energy can be transferred to and from the surroundings and Examples include a sealed container, a pressure cooker, and a greenhouse. ★ Isolated System: ★ Definition: An isolated system cannot exchange either matter or energy with its surroundings. ★ Characteristics: Both mass and energy remain constant within the system, Perfect isolation is theoretically impossible, but systems can be approximated to be isolated and Examples include an insulated thermos bottle, and the universe is often considered an isolated system. ➔ Le Chatelier’s principle: ★ Le Chatelier’s Principle is about the position of Equilibrium during a reversible reaction and specifically it reacts with temperature, pressure & concentration. ★ Le Chatelier's principle states that a system at equilibrium will move in the opposite direction to undo changes and relieve imposed stress, such as concentration, pressure, or volume alterations. ★ Increasing the concentration of a reactant causes the reaction to shift right, while increasing the concentration of a product causes it to shift left. ★ Changes in volume affect equilibrium: increasing volume shifts the reaction left, while decreasing volume shifts it right, as the system tries to increase total pressure by moving to the side with more moles of gas. ★ Adding a catalyst has no effect on equilibrium position, as it speeds up forward and reverse reactions equally without changing reactant or product concentrations. ★ Increasing the partial pressure of a reactant shifts the reaction right, while increasing the partial pressure of a product shifts it left, as the system attempts to decrease the partial pressure of the affected component. ➔ Haber’s Process ★ Fritz Haber was a German chemist and winner of the 1918 Nobel Prize for Chemistry for his successful work for developing a method to synthetically fix nitrogen from the air. ★ The Haber-Bosch process combined nitrogen and hydrogen to form ammonia in industrial quantities for production of fertilizer and munitions.  ★ This breakthrough has had profound implications for agriculture and industry, fundamentally changing food production and various chemical processes. ★ In the Haber process, the atmospheric nitrogen (N2) is converted to ammonia (NH3) by reacting it with hydrogen (H2). Here a metal catalyst is used and high temperatures and pressures are maintained. ★ The 3 main raw materials for the process are:- Air, which supplies the nitrogen ★ Natural gas and water supply the hydrogen and the energy needed to heat the reactants ★ Iron is the catalyst and does not get used up. ★ Haber’s discovery allowed for the large scale production of fertilizers that began during the green revolution and continues today. ★ Today, the Haber process is still necessary because it produces ammonia, which is vital for fertilizers and many other purposes. ★ Every year, the Haber cycle produces around 500 million tons of fertilizer (453 billion kilograms). This fertilizer helps feed about 40% of the population of the world. ➔ Ethical Implications of Science (Criteria D) ★ Ethical implications in Agriculture Positive impact of fertilizers - Fertilizers help plants grow better and produce more food. This helps feed more people and can reduce hunger worldwide. - Example: Using fertilizers can increase crop yields, meaning farmers can grow more food on the same amount of land. Negative Impact of Overusing Fertilizers - Environmental Harm: Overusing chemical fertilizers can pollute rivers and lakes, harming fish and other aquatic life. - Soil Damage: It can also damage the soil, making it less fertile over time. - Example: Runoff from fields treated with too much fertilizer can lead to algal blooms in water bodies, which deplete oxygen and kill aquatic life. ★ Ethical implications in Medicine Genetic Modification - Concerns: Genetic modification involves changing the DNA of living organisms. This can lead to ethical questions about safety, fairness, and the natural order of life. - Example: Gene therapy can cure diseases but has unknown long-term effects. Vaccines - Benefits: Vaccines prevent diseases, saving millions of lives. They protect not only the person vaccinated but also the community by preventing the spread of diseases. - Example: Polio vaccines have nearly eliminated the disease. ★ Ethical Implications in Energy Production Fossil Fuels - Environmental Impact: Contributes to global warming and pollution. - Health Risks: Causes respiratory issues. - Example: Emissions from cars and factories. Renewable energy - Benefits: No greenhouse gasses, sustainable. - Example: Solar panels generate clean electricity. ★ Ethical Implications in Technology Artificial Intelligence - Privacy: Data collection can invade privacy.  - Job Displacement: AI can replace human jobs. - Bias: AI can reflect data biases. - Example: Biased facial recognition systems. ➔ Endothermic and Exothermic reactions ★ Endothermic Reactions are absorbed ★ Exothermic Reactions are Released ➔ Concentration vs Time graphs ➔ Exothermic and Endothermic graphs ★ ➔ Reaction vs Time graphs ★ Unit 2: Consequences ➔ Acid Base ★ Some Reactions of Acid and Bases: - NaOH + HCL → NaCl + H2O (Acid + Base) - NH4OH + HCL → NH4Cl + H2O (Strong acid + weak base) - CH3COOH + NaOH → CH3COONa + H2O (Weak acid + strong base) - CH3COOH + NH4OH → CH3COONH4 + H2O (Weak acid + Weak base) - NaHCO3 + HCL → NaCl + H2O + CO2 (Metal Carbonate + Strong acid) - Ca(OH)2 + CO2 → CaCO3 + H2O (Non-metallic oxide with base) ★ Strength vs concentration and Equilibrium: Strength of an acid (or a base): - In the diagram on the left, the hydrochloric completely dissociates into H+ and Cl. This means that HCl is a strong acid. In the diagram on the right, the acetic acid only partially dissociates into H+ and CH3COO-. This means that CH3COOH is a weak acid. Concentration of an acid (or a base): - In the diagram on the left, there are more molecules of HCl than on the right. This means the solution on the left can be described as being more concentrated while the solution on the right can be described as being more dilute. ➔ Indicators ★ Blue litmus paper turns red in acidic solution ★ Red litmus paper turns blue in Alkaline solution ★ Universal indicator provides a comprehensive pH measurement across the entire 0-14 scale, displaying a rainbow-like color spectrum for easy identification of acidity or alkalinity levels. ★ Litmus paper offers a simple binary acid-base test, with its blue side turning red in acidic conditions and red side turning blue in alkaline environments. ★ Phenolphthalein is crucial for strong acid-strong alkali and weak acid-strong alkali titrations, changing from colorless to fuchsia pink at a precise pH of 8.2 ★ Methyl orange serves as an indicator for strong acid-strong alkali and strong acid-weak alkali titrations, transitioning from red to yellow between pH 3.1 and 4.4 ➔ pH and its applications ★ pH scale: The pH scale ranges from 0 to 14 - pH < 7: Acidic solution - pH = 7: Neutral solution - pH > 7: Basic (alkaline) solution ★ pH=−log10​[H+] ★ If the H+ ions are given, then it's this equation: pH = -log10 [H+] ★ If the pH is given, then it's this equation: [H+] = 10-pH ➔ Acid Rain ★ Acid Deposition is the process by which acid-forming pollutants are deposited on the earth’s surface. ★ There are two main types of acid deposition, which are wet acid deposition and dry acid deposition. ★ There are multiple effects of acid deposition. The first one is Impact on materials: The building materials marble and limestone are both forms of calcium carbonate The second  one is Impact on plant life: Acid rain shown to be direct cause of slower growth, injury or death plans ★ Acid rain refers to the solution with a pH below 5.6 and is the rain containing an excess of acid, usually caused by the release of sulfer dioxide and nitrogen oxide from burning fossil fuels, and has severe environmental and socio economic impacts. ★ Environmentally, it damages the forests, wildlife as well as the soil in significant amounts. It damages forests by leaching essential nutrients from the soil, acidifies water bodies harming aquatic life, and degrades soil fertility. ★ Socio-economically, it deteriorates infrastructure, like for example Taj Mahal and poses health risks due to the respiratory issues caused by pollutants. Economic sectors such as agriculture, forestry, and tourism also suffer. ★ To mitigate these impacts, scientific advancements like flue-gas desulfurization and catalytic converters have been implemented to reduce SO₂ and NOₓ emissions. The adoption of clean energy sources further decreases reliance on fossil fuels. ★ Regulatory measures, including emission standards, cap-and-trade programs, and international agreements, have successfully reduced acid rain in many regions. ★ For example, the Clean Air Act in the USA and the Gothenburg Protocol in Europe have led to significant emission reductions. Overall, continued innovation and regulatory efforts are crucial in combating the detrimental effects of acid rain. Unit 3: Evidence ➔ Qualitative and Quantitative Data ★ Quantitative observations are measurements that provide numerical data about an object or phenomenon. These observations are objective and can be counted, measured, and expressed using numbers. They are often obtained using instruments or tools and are essential for scientific experiments because they allow for consistency, accuracy, and reproducibility. ★ Qualitative observations describe qualities or characteristics that are not expressed in numbers. These observations are subjective and based on the senses and these involve the collection of numerical data during an experiment. ➔ How was the periodic table developed? ★ The modern periodic table is split into groups (columns) and periods (rows). The elements are arranged in order of increasing atomic number. The arrangement of elements in the periodic table enables chemists to predict the physical properties and chemical reactions from the elements involved. ➔ What characterizes a metal? ★ The periodic table is often separated into metallic elements and non metallic elements, but what is a metal? Characteristically, metals: are good conductors of heat and electricity are malleable—they can be hammered into different shapes are ductile—they can be drawn into wires are shiny when pure and unreacted are sonorous—they ring when struck tend to have high densities have high melting and boiling points tend to lose electrons to form cations (positively charged ions) ➔ What are transition elements? ★ Location: Transition elements are found in Groups 3 to 12 of the periodic table. ★ General Properties: - They are all metals, hence commonly known as transition metals.  - They tend to form colorful compounds, often used in pigments and dyes. - Transition metals often act as catalysts, helping to speed up reactions without being consumed. - Many can form ions with variable charges (e.g., Chromium can form Cr³⁺ and Cr⁶⁺ ions). ★ Unpredictability: Unlike other groups (e.g., alkali metals or halogens), transition metals' properties do not follow simple, predictable patterns. ➔ Organic Chemistry ★ Allotropes are essential for us in life ★ Covalent bonds occur between nonmetals sharing electrons with non-polar bonds having equal electron distribution and polar bonds having unequal distribution due to differences in electronegativity. ★ Ionic bonds form between metals and non-metals through electron transfer resulting in oppositely charged ions attracting each other and forming crystal lattices. ★ Covalent bonds are represented by dot and cross diagrams showing only valence electrons, while in displayed formulas, a straight line represents a covalent bond between atoms. ★ Covalent compounds typically have low melting and boiling points and are volatile due to their non-polar nature and weak intermolecular forces. ★ Ionic Bond includes: NaCl, MgO, K2O, Na2, ZnO, NaHSO4, NaOH, NaHCO3, Lia ★ Covalent bonds includes: CO2, NO2, SO2, H2O, HCL, H2SO4, CH3COOH, C6H12O2 ★ There are two types of Ions Cation & Anion ➔ Lewis electron dot structure ★ The Lewis electron dot structure, also known as the Lewis structure, represents the valence electrons (outermost electrons) in an atom, ion, or molecule. It’s a useful way to visualize bonding in molecules and determine the arrangement of atoms in a compound. ★ Valence Electrons: - These are the electrons in the outermost shell of an atom and are involved in bonding. - The number of valence electrons is typically indicated by the group number in the periodic table for main-group elements ★ Octet Rule: - Most atoms (especially in the second period of the periodic table) strive to achieve an octet, or 8 electrons, in their outer shell. - Hydrogen is an exception, aiming for only 2 electrons in its outer shell (duet). ★ Electron Pairing: - Electrons are represented as dots around the atomic symbol. - Pairs of dots between atoms represent shared electrons or covalent bonds. - Lone pairs (non-bonding pairs) are pairs of dots that are not shared with other atoms. ChatGPT plan: Day Time Subtopic Method of Study Checklist October 14th 4:30 to 5:30 Equilibrium Review notes and Done create concept 6:30 to 7:00 Equilibrium Quick Review and Done Quiz myself October 15th 4:00 to 4:50 Writing and Balancing Watch Videos and Not yet … Equations practice problems October 16th 4:30 to 5:30 Le Chatelier’s principle Review notes and Not yet … create real-life examples. 5:40 to 6:40 Le Chatelier’s principle Quick Review and Not yet … Quiz myself October 17th 4:00 to 4:50 Haber’s Process Watch a video on the Not yet … Haber Process 7:30 to 8:15 Haber’s Process Quick Review and Not yet … Quiz myself October 18th 4:30 to 5:30 Ethical Implications Review notes and Not yet … summarize key points October 19th Whenever Free Concentration vs Time Analyze example Not yet … Graph graphs and create own graphs based on past SA paper Whenever Free Endothermic vs Analyze example Not yet … Exothermic Graph graphs and go through textbook as well as SA paper’s October 20th Whenever Free Reaction vs Time Graph Do practice problems Not yet … and review notes Whenever Free Open, Closed & Isolated Review notes and go Not yet … Systems through the diagrams from the textbook October 21st 4:30 to 5:30 Acid Base Reactions Review notes and Not yet … practice balancing.  6:30 to 7:00 Acid Base Reactions Memorize all the Not yet … reactions and quiz myself October 22nd 4:00 to 4:50 Strength vs Review notes and go Not yet … Concentration and through presentation Equilibrium shared on toddle 7:30 to 8:15 Strength vs Review notes and Not yet … Concentration and practice problems Equilibrium October 23rd 4:30 to 5:30 Indicators Review notes and Not yet … quiz myself 5:40 to 6:40 pH and its applications Review notes and Not yet … practice problems October 24th 4:00 to 4:50 Acid Rain Go through notes Not yet … and create a summary. 7:30 to 8:15 Review both units Quick review of all Not yet … topics covered so far. October 25th Not yet … Not yet … Concept Map for Equilibrium: Quiz for Equilibrium: https://quizizz.com/join/quiz/5cfe3b96f4b271001b8958cf/start Criteria B & C Candles are made up of various types of wax which are a type of hydrocarbon. A student wanted to compare the time it took different candles to burn. One candle was in a metal holder and the other was not. Q.1: Formulate a hypothesis for the student's question Ans: If the candle is burnt in the mental candle holder, then the time will decrease compared to the candle that is not in the mental candle holder because the metal conducts heat and spreads faster. A student wanted to investigate the effect of altitude on how quickly a candle burns, so she took some candles on a camping trip up a mountain. Her processed data is shown below in the table below Q.1: State the rate of wax combustion at an altitude of 3720m in standard form. Ans: Rate of wax combustion at an altitude of 3720m in standard form would be: 1.06 × 10-1g/min The student produced a graph of her results, which is shown below, The student repeated the experiment the following day. The results are in the table below The equipment set up on each day is shown below Q: Outline why the sets of results are different and suggest how the rate of wax combustion would be affected in each of the above case Ans: The sets of results are different because the first experiment is carried out in a closed place, while the second one is carried out in an open environment. In the first experiment, there is more heat within the enclosed environment, which causes the candle to combust faster. However, in the 2nd experiment, there is no enclosure, and the candle combusts much slower. His results are shown below: Q.1: State the Independent Variable and the Dependent Variable in this investigation Ans: - IV: Fragranced of candles - DV: Time taken to burn Q.2: Calculate the average burn time for the strawberry candle 32.0 + 28.5 + 29.5 90 Ans: 3 ⇒ 3 ⇒ 30 ℎ𝑜𝑢𝑟𝑠 Q.3: The student's friend examined the data and suggested that the average burn time for a vanilla candle should be 28.5 hours and not 27.1 hours. Suggest a reason for this different average time. Ans: The student’s friend says that the average burn time for a vanilla candle should be 28.5 and not 27.1 because he feels that the second value 24.3 is an outlier, and therefore it is having an impact on the average value. Therefore, he has taken an average without considering the outlier, which is how he got 28.5. Q.4: The student hypothesized that the candle with vanilla fragrance would take a longer time to burn because the candle had a smaller surface area. Use the data in the table above to evaluate the validity of the students hypothesis. Ans: The hypothesis is invalid because the table above mentions that the average burn time of the vanilla fragrance would be 27.1 hours, while the average burn time of the strawberry fragrance would be 30 hours. So according to the results, the vanilla fragrance would take a longer time to burn because the candle had a smaller surface area. Q.5: Suggest one improvement to increase the validity of the method. Justify your answer. Ans: The containers used for both the wax aren’t the same, it would be better to have them as the same to increase the validity of the method because the vanilla glass jar is much bigger and wider than the strawberry glass container, which can have a big impact on results. So, the 2 containers should be identical. Overall Question and Answer Here’s a question paper designed for the IB MYP 4 Chemistry curriculum, covering the acid-base concepts and associated topics, and integrating equation writing and balancing into context-based scenarios: --- **IB MYP 4 Chemistry Question Paper** **Topic:** Acid-Base Reactions, Indicators, pH, and Acid Rain **Total Marks:** 40 --- ### Section A: Scenario-Based Questions (20 Marks) 1. **Neutralization in Real-World Applications** The process of treating wastewater in industries often involves adding calcium hydroxide (\(\text{Ca(OH)}_2\)) to neutralize excess sulfuric acid (\(\text{H}_2\text{SO}_4\)). **a)** Write the balanced chemical equation for this reaction, identifying the salt formed. (3 Marks) **b)** Explain why neutralization is important in wastewater treatment. How does it impact the environment if left untreated? (3 Marks) 2. **Strength vs. Concentration of Acids**  Imagine you have two samples of hydrochloric acid: Sample A with a low concentration but high strength, and Sample B with a higher concentration but lower strength. **a)** Explain the difference between strength and concentration in this context. (2 Marks) **b)** How would the pH of the two samples differ? Justify your answer based on the concepts of strength and concentration. (2 Marks) 3. **pH and Daily Applications** A gardener needs to lower the pH of soil for certain acid-loving plants. She decides to use vinegar, which contains acetic acid (\(\text{CH}_3\text{COOH}\)). **a)** Write and balance the chemical equation for the reaction between acetic acid and sodium hydroxide (\(\text{NaOH}\)). (3 Marks) **b)** Explain how pH influences plant growth and why some plants require a lower pH. (3 Marks) 4. **Acid-Base Indicators in Different pH Ranges** A laboratory experiment requires students to test the pH of three solutions: an acidic solution, a neutral solution, and a basic solution. The available indicators are litmus and phenolphthalein. **a)** Choose the most suitable indicator for each solution, and explain your choices. (3 Marks) **b)** Describe the color changes you would observe with each indicator in acidic, neutral, and basic environments. (3 Marks) --- ### Section B: Theoretical and Analytical Questions (20 Marks) 5. **Acid Rain and Its Effects** Acid rain is formed when sulfur dioxide (\(\text{SO}_2\)) reacts with water vapor in the atmosphere to form sulfurous acid (\(\text{H}_2\text{SO}_3\)). **a)** Write a balanced chemical equation for this reaction. (2 Marks) **b)** Discuss two ways in which acid rain impacts the environment and buildings. (3 Marks) 6. **Acid-Base Equilibrium and Le Chatelier’s Principle** Consider the weak acid equilibrium of acetic acid in water: \[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \]  **a)** Explain how adding a strong acid, such as \(\text{HCl}\), would affect the equilibrium position according to Le Chatelier’s Principle. (3 Marks) **b)** Describe one practical application where controlling the equilibrium of an acid-base reaction is beneficial in industry. (2 Marks) 7. **pH Calculation and Concentration** Calculate the pH of a solution with a hydrogen ion concentration \([ \text{H}^+ ] = 1 \times 10^{-3} \text{ mol/L}\). Show all your work. (3 Marks) 8. **Importance of Buffer Solutions** Buffer solutions are used to maintain pH stability in biological and chemical processes. **a)** Define what a buffer solution is and describe how it works. (3 Marks) **b)** Explain why buffer systems are crucial in human blood. (2 Marks) 9. **Application of Neutralization Reactions in Everyday Products** Many antacid tablets contain magnesium hydroxide (\(\text{Mg(OH)}_2\)) to neutralize stomach acid (\(\text{HCl}\)). **a)** Write the balanced chemical equation for the reaction between magnesium hydroxide and hydrochloric acid. (2 Marks) **b)** Why is balancing equations crucial in calculating the dosage of ingredients in medicinal products? (2 Marks) --- *End of Paper*