Final Exam Studying Material PDF

How Molecules Mix Chapter 7 Four Different Types of Dipole Attractions ! Dipole : - Electron unevenly distributed in a molecule. H - Cl ( Dipole ) | Δ E.N = 0.9...

How Molecules Mix Chapter 7 Four Different Types of Dipole Attractions ! Dipole : - Electron unevenly distributed in a molecule. H - Cl ( Dipole ) | Δ E.N = 0.9 Cl - Cl ( Not dipole ) | Δ E.N = 0 - Extreme cases are present in ionic compounds. Dipole = 2 opposite pole - Water exhibits a weaker dipole type called a polar molecule. Molecular Attractions Involving Dipoles ( intermolecular forces ) : Questions : define - which one has the strongest attraction - what is the type of attraction in the following reaction ( polar ) 1 Ion - Dipole Attraction : Interaction between ionic charge and molecular dipole. - Collective attraction from many molecules. + - - i 2 - NaCl + O = HCl + NaO + + Ion - Dipole attraction H H 2 Dipole - Dipole Attraction : The attraction between two dipoles. H2O + H2O / HF + HF / HCl + HCl Dipole - Dipole attraction ( Hydrogen bond ) H + N/O/F Hydrogen bond : An unusually strong dipole-dipole attraction between molecules that E.N increases have a hydrogen bonded to a highly electronegative atom. ( polar ) - ( nonpolar ) 3 Dipole - Induced Dipole Attraction : Interaction between a permanent dipole and a dipole–induced dipole. - Weaker than dipole–dipole attractions. 1) H ( Repulsion ) + - - + + - H2O + O2 > H +O - + - + - O+ - + +O - + - ( Dipole induced in a nonpolar molecule by surrounding 2) H ( Attraction ) + - + - + - dipole containing molecules “ nonpolar > polar “ ) H +O - + - + +O - + - +O - + -  ( nonpolar) - ( nonpolar ) 4 Induced Dipole - Induced Dipole Attraction : The attraction between two induced dipoles. - Temporary dipoles are due to the momentary arrangement of electrons. - Temporary dipoles can induce dipoles on other nonpolar molecules. - Has largest effect in the largest atoms and molecules. - Also called dispersion forces. Teflon ( nonpolar ) Ar + Ar ++Ar-- ++Ar-- / I / F2 + - + - 2 ! Concept Check Distinguish between a dipole–dipole attraction and a dipole–induced dipole attraction. The dipole–dipole attraction is stronger and involves two permanent dipoles. The dipole–induced dipole attraction is weaker and involves both a permanent and temporary dipole. Distinguish between a dipole–induced dipole attraction and an induced dipole–induced dipole attraction. The dipole–induced dipole attraction is stronger and involves both a permanent and temporary dipole. The induced dipole– induced dipole attraction is weaker and involves two temporary dipoles. How does the electron distribution in an oxygen molecule change when the hydrogen side of a water molecule is nearby? Because the hydrogen side of the water molecule is slightly positive, the electrons in the oxygen molecule are pulled toward the water molecule, inducing in the oxygen molecule a temporary dipole in which the larger side is nearer the water molecule (rather than as far away as possible). Methanol, CH3OH, which can be used as a fuel, is not much larger than methane, CH4, but it is a liquid at room temperature. Suggest why. The polar oxygen–hydrogen covalent bond in each methanol molecule leads to hydrogen bonding between molecules. These relatively strong interparticle attractions hold methanol molecules together as a liquid at room temperature. ! A Solution Is a Single-Phase Homogeneous Mixture Types of mixture I Homogeneous Heterogenous - Same phase - different phases - Can be mixed - Can’t be mixed Milk + Water Sand + Water Solution : Homogenous mixture of a single phase. * Sugar dissolved in water is a liquid solution. * Gemstones are solid solutions. * Alloys are solid solutions. * Air is a gaseous solution. Parts of a solution : - Solvent : is the largest component of a solution. - Solute : is the smallest component of a solution ( makes up the other components ). Sugar Types of solutions based on solute amount Water Dissolving : The process of a solute mixing in a solvent. I Unsaturated Saturated Supersaturated 150 g 200 g 250 g 100 mL 100 mL 150 mL 50 g I = Less solute present Solute and solvent can mix Some amount of solute than will dissolve in the well together, and no more will settle to the bottom, solution, solute and solute will dissolve in the and it will not dissolve in solvent can mix well solution. the solution, Why ? together, and more of a because all molecules of solute will dissolve. solvent are used.  Concentration Is Given as Moles per Liter Concentration : A quantitative measure of the amount of solute dissolved in a solution. Directly proportional amount of solute (mass) Standard units : Concentration = amount of solution ( volume ) g / L = mL / L = g / m 3 Inversely proportional 23 Mole : Chemical amount of a substance, equal to 6.02 × 10 atoms or molecules ( = an Avogadro’s number ) Molarity : The concentration of a solution expressed in moles of solute per liter of solution. ( Molar concentration ) Number of moles of solute Mass of substance (g) Molarity (M) = Mole (m) = Volume of solution in L Molecular mass Standard units : M = moles / L mole Solubility Solubility : Ability of a solute to dissolve in a solvent. - If a solute has any appreciable solubility in a solvent, then that solute is said to be soluble in that solvent. - Depends on number and types of interactions. Types of solubility Infinitely soluble Insoluble Solute has no practical point Solute does not dissolve in solvent of saturation in a solvent. to any appreciable extent. Polar + Polar ( Ethanol and water ) Polar + Nonpolar ( Glass and water )  Temperature Effects on Solubility : - Solubility increases with temperature due to increased kinetic energies. - Solid solute that forms from solution upon cooling is called a precipitate. When a sugar solution saturated at a high temperature is allowed to cool, some of the sugar usually comes out of solution and forms what is called a precipitate. When this occurs, the solute, sugar in this case, is said to have precipitated from the solution. - On gases : Gas solubility decreases with increased temperature. Gas solubility increases with increased pressure. - Due to the increased kinetic energy and the solute molecules escaping the solution. Solvent Polar Nonpolar Solute Ionic ( has the highest solubility ) Polar Nonpolar  Concept Check What is the solvent in the gaseous solution we call air? Nitrogen is the solvent, because it is the component present in the greatest quantity. Which one is more concentrated? 2 gm / 100 mL or 5 gm / 100 mL Dilute More ( only when concentrated the solvent is water “aq” ) How many moles in 3 grams of carbon in CO2? Mole = mass of substance / molecular mass of substance = 3 / ( 12 + 2 x 16 ) = 3 / 44 = 0.068 mole Calculate the molarity of 4 grams of chlorine of HCl in 3 litres of solution. 1 ) Mole = mass of substance / molecular mass of substance = 4 / 36.5 = 0.1 mole 2 ) Molarity = number of moles of solute / volume of solution Molarity = 0.1 / 3 = 0.03 mole/L ( M ) 2 molar solution = 2M How many moles of sucrose are in 0.5 liter of a 2-molar solution? How many molecules of sucrose is this? Number of moles of solute = Molarity x volume of solution = 2 x 0.5 = 1 mole 23 1 mole = 6.02 x 10 molecules A saturated aqueous solution of sucrose contains 200 grams of sucrose and 100 grams of water. Which is the solvent: sucrose or water? Water is the solvent.  How Chemicals React Chapter 9 Chemical Equation Chemical reaction : describe how atoms are rearranged. Chemical equation: A representation in which reactants are written before an arrow and products are written after the arrow / is a short way to show the chemical reaction. C + O2(g)> CO (g) - Reactants : Reacting substances. (s) 2 - Products : Substances that are formed from a chemical reaction ( New substances ). Phases are shown by abbreviations : - (s) for solid - (l) for liquid - (g) for gas - (aq) aqueous “ When compounds are dissolved in water “ Coefficients Coefficient : Denote the number of each type of atom or molecule present, and is shown before each type of atom or molecule ( = number of moles, we can change it ) / Integers used to indicate the ratio by which reactants react and products form. 1 C(s)+ 1 O > 1 CO 2(g) 2(g) Coefficient - subscript ( we can’t change it ) Balance Chemical Equation - The same number of each type must go into and come out of a reaction. - Demanded by the law of conservation of mass. – In balancing, only the coefficients can be changed. - Coefficient of 1 is omitted. 2 H +1O > 2H O 3 H (g) + N2(g) > 2NH 2(g) 2 (g) 2 (g) 2 3(g) Balancing equations quick guide : 1. Focus on one element at a time. 2. Move on to next element and balance. 3. Continue through all the elements. 4. Repeat 1–3 until all elements are balanced.  The Law of Mass Conservation The law of mass conservation : Atoms are neither created nor destroyed in a chemical reaction—they are simply rearranged. The number and type of atoms before a reaction = the number and type of atoms after the reaction. Counting Atoms and Molecules by Mass Because different atoms and molecules have different masses, there are different numbers in a given mass. - Atomic masses are given on the periodic table. One carbon atom is roughly 12 amu. - Molecular mass is the sum of the atomic masses. O2 is about 32 amu (~16 amu from each O). Converting between Grams and Moles From periodic table Moles Mass (g) Molecules 23 C 1 12 6.02 x 10 23 CO2 1 44 6.02 x 10 23 2C 2 24 (2)x 6.02 x 10 One mole of an atom is equal to the amount of mass in grams. One mole of a molecule is equal to the molecular mass in grams. 23 Molar mass : the mass of 1 mole of the substance / the mass of 6.02 × 10 of the item in the mole. - Unit is grams per mole.  Concept Check How many oxygen atoms are indicated by the following balanced equation? 3O ×2O 2(g) 3(g) There are six oxygen atoms. Before the reaction, these six oxygen atoms are found in three O2 molecules. After the reaction, these same six atoms are found in two O3 molecules. Balance these following equations : - P4O10 + 6 H2O × 4 H3PO4 - 6 CO2 + 6 H2O × C6H12O6 + 6 O2 - 2 C8H18 + 25 O2 × 16 CO2 + 18 H2O - 3 H2 + 3/2 O2 × 3H2O How many molecules in 5 moles of H2O? 23 1 mole = 6.02 x 10 molecules 5 moles = x molecules 23 x = (5 x 6.02. x 10 ) / 1 23 x = 30.1 x 10 molecules How many molecules in 20 grams of CO2? - We can directly find the number of moles moles 1 ) Mole = mass of substance / molecular mass of substance if we have the mass (g). = 20 / 44 = 0.45 mole - We can directly find the number of molecules if 23 2 ) 1 mole = 6.02 x 10 molecules we have the number of moles. 0.45 moles = x molecules - We can find the number of molecules if we have 23 x = (0.45 x 6.02. x 10 ) / 1 the mass (g) by finding number of moles first. 23 x = 2.709 x 10 molecules How many atoms are in a 6.941-gram sample of lithium, Li (atomic mass = 6.941 amu)? Because this number of grams of lithium is numerically equal to the atomic mass, 23 6.02 → 10 atoms are in the sample, which is 1 mole of lithium atoms.  Chemical Reactions Can Be Exothermic or Endothermic Reactions may either absorb or release energy. The change in energy is due to the formation or breaking of chemical bonds. Bonding energy : The energy to break or form a bond. Bond energy ( Net energy of reaction ) = Energy absorbed - energy released Exothermic Endothermic - Exothermic : If energy is released. - Endothermic : If energy is absorbed. E = -ve E = +ve More E Less E - Negative energy is the energy - Positive energy is the energy released as the bond forms(-E) absorbed as a bond breaks(+E) H + H > H2 H >H+H 2 - Less energy is contained in the - More energy is contained in the product’s bonding. product’s bonding. The amount of energy required to pull two bonded atoms apart, which is the same as the amount released when they are brought together.  Energy is conserved in a chemical reaction. Laws of Thermodynamics : 1. Thermodynamics is the area of science concerned with energy’s roles. 2. The flow of energy is always a one-way trip from where it is concentrated to where it is less concentrated, or “spread out.” 3. First law of thermodynamics states that energy does not appear or disappear. - You can’t win because you can’t get any more energy out of a system than you put into it. You can’t break even because no matter what you do, some of your energy will be dispersed as ambient heat. Energy tend to disperse. - One of the main driving forces of chemical and physical changes. - Reactions that concentrate energy do not tend to occur. - Described by the second law of thermodynamic. The Second Law of Thermodynamics : Any process that happens by itself results in the net dispersal of energy. For example, heat naturally flows from a higher-temperature object to a lower temperature ⬇it is concentrated (a hot pan) to object because, in doing so, energy is dispersed from where where it is spread out (the cooler kitchen). Chemical Reactions Are Driven by the Spreading of Energy Entropy ( The Second Law of Thermodynamics ) : Measure of the spreading of energy ( energy wasted ). - Increase in entropy corresponds to a spreading of energy. - Exothermic = high entropy ‫مد ا?اء‬B : ‫ على سبيل ا?ثال‬,‫نتروبي للمحيط وليس للمادة نفسها‬%‫يزيد ا‬.‫نتروبي للمحيط‬%‫نتروبي للماء ا?تجمد ويزيد ا‬%‫ فيقل ا‬,‫تفاعل طارد‬ * Car produces smoke, so the entropy is high. * The sun is truly a “hothouse”— dispersing enormous amounts of energy from exothermic nuclear reactions. A tiny fraction of the energy is used to drive photosynthesis, which is vital for plants and plant-eating creatures like us.  Chemical Reactions Can Be Slow or Fast Reaction rate : Speed of a reaction / How time is taken to complete the reaction ( reactants > products ) / How quickly the concentration of reactants decreases and the concentration of products increases. Concentration of reactants Temperature of the reactants - On gases : rate reaction is inversely proportional to the temperature. Orientation The speed of a reaction depends upon - Reactants must collide in the correct orientation to react High concentration / temperature / pressure = High reaction rate Correct orientation = High reaction rate Why ? Because of the collision between reactants. Pressure - Reactants must come in contact to react. - The more interactions or the higher the energy, the faster the overall rate.  Activation Energy Activation Energy (Ea) : The minimum energy required to overcome the initial breaking of bonds in reactants. - Can be viewed as an energy barrier the reaction must overcome. - The faster moving a molecule, the more energy present. - Reactants must be moving fast enough (have sufficient kinetic energy) to overcome the energy of activation. E2 E(P) Ea= E2 - E1 E= E(P) - E(R) E(R) E1 Catalysts speed up a reaction. - Not consumed in the process of the reaction. - Lowers the overall activation energy needed. Chlorofluorocarbons (CFCs) : - Chlorine acts as a catalyst to destroy ozone in the stratosphere. Cl + O > ClO + O2 3 ClO + O3> Cl + 2O2 - Depletion of stratospheric ozone leads to the “ ozone hole “.  Concept Check Determine if the following reaction is exothermic or endothermic : * Bond energy ( Net energy of reaction ) = Energy absorbed - energy released -2H +O ×2H O 2 2 2 Bond energy = ( 2 x 436 + 498 ) - ( 2 x 928 ) = - 486 kJ / mol ( Exothermic ) - N + O × 2 NO 2 2 Bond energy = ( 946 + 498 ) - ( 2 x 631 ) = + 182 kJ / mol ( Endothermic ) Do all covalent single bonds have the same bond energy? No. Bond energy depends on the types of atoms bonding. The H–H single bond, for example, has a bond energy of 436 kilojoules per mole, but the H– O single bond has a bond energy of 464 kilojoules per mole. Not all covalent single bonds have the same bond energy. Where does the net energy released in an exothermic reaction go? This energy goes into increasing the speeds of reactant atoms and molecules and often into electromagnetic radiation such as light. Should the following reaction be endothermic or exothermic? 2N2O > O2 + 2N2 No calculations are necessary. This reaction is endothermic because it involves only the breaking of a chemical bond. Sugar crystals form naturally within a supersaturated solution of sugar water. Does the formation of these crystals result in an increase or a decrease in entropy? The formation of these sugar crystals results in an increase in entropy. Your clue to an increase in entropy here is that the crystals form “on their own,” a spontaneous process and thus one that must result in an entropy increase. An internal-combustion engine works by drawing a mixture of air and gasoline vapors into a chamber. The action of a piston then compresses these gases into a smaller volume prior to ignition by the spark of a spark plug. What is the advantage of squeezing the vapors into a smaller volume? queezing the vapors into a smaller volume effectively increases their concentration and hence the number of collisions between molecules. This, in turn, promotes the chemical reaction. How is a catalyst different from a chemical reactant? A catalyst is not used up during a chemical reaction. Instead, it is released as its original self. The catalyst can then serve to catalyze more reactions. A chemical reactant, by contrast, is consumed during a reaction as it is transformed into a chemical product. If you take two materials and put them together, will they react to form new materials? If the reaction results in the spreading of energy (an increase in entropy) then the answer is yes.  Practice questions The main difference is that "molecular mass" is used for covalently bonded molecules, while "formula mass" is used for ionic 1- The difference between molecular mass and formula mass : compounds. Molecular mass’s unit is gram, formula mass’s unit is amu ( we can find them by using the same way for both ) 2- Determine the intermolecular force of the following compounds : a- KMnO3 b- HCl + HCl O2 + O2 Ion-dipole Dipole-dipole Induced dipole-induced dipole 3- Liquid > ice, does entropy increase or decrease ? Entropy decreases 4 - Find the type of each reaction : a- b- 30 30 20 20 Δ E ( net energy )= E2 - E1 Δ E ( net energy )= E2 - E1 = 30-20 = 20-30 = +10 kJ/mole ( Endothermic ) = -10 kJ/mole ( Exothermic ) 5- calculate the activation energy. 70 Δ Ea = E2 - E1 = 70 - 40 = 30 kJ/mole 40 6- How many gram of sugar are in 12.2 L water that have the concentration of 0.5 g/L? Concentration = mass / volume 0.5 = x / 12.2 x = 6.1 g 7- 81.6 g of BeCl2 was dissolved in water for making 954 mL of solution. Calculate molar concentration. 1) mole = mass (g) / molecule mass 2) Molarity = number of moles of solute / volume of solution (L) = 81.6 / (9+35x2) = 1.03 / 0.954 = 1.03 mole = 1.08 M ( mole / L ) 8- How many moles of CO2 are formed if 48 grams of CH4 undergo reaction with O2? 1) CH4 + 2 O2 > CO2 + 2 H2O 3) 1 mole of CH4 > 1 mole of CO2 3 mole of CH4 > x mole of CO2 2) 1 mole of CH4 > 16 g of CH4 x = 3 mole of CO2 x mole of CH4 > 48 g of CH4 x = ( 48 x 1 ) / 16 x = 3 mole of CH4 9- Calculate number of mole of Fe required to produce 30.8 gram of Fe2S3. 1) 4Fe + 6S > 2Fe2S3 ( it is not the correct balancing, just for solving this question ) 2) 2 mole of Fe2S3 > 416 g of Fe2S3 3) 4 mole of Fe > 2 mole of Fe2S3 x mole of Fe2S3 > 30.8 g of Fe2S3 x mole of Fe > 0.148 mole of Fe2S3 x = ( 30.8 x 2 ) / 416 x = 0.3 mole of Fe x = 0.148 mole of Fe2S3  Acids and Bases Chapter 10 Acids & Bases & salt Acids Bases 1 The Arrhenius Theory Acids/Bases are substances that ionize in water to yield ionize in water to yield dissociate in water to yield electrically hydrogen ions (H+). hydroxide ions (OH×). + - charged atoms or molecules, called ions. HCl > H + Cl NaOH > Na+ + OH - 2 Bronsted-Lowry Theory Donate an H+. Accept an H+. Defines acids and bases based on hydrogen ions (H+). HCl donates a hydrogen ion Water accepts the hydrogen ion and therefore is an acid. and therefore is a base. (Conjugate (Conjugate base) acid) Water donates a hydrogen ion Ammonia accepts the hydrogen and therefore is an acid. ion and therefore is a base. (Conjugate (Conjugate base) acid) 3 Lewis Theory Accept a lone pair of electron. Donate a lone pair of electron. More general than the Brønsted–Lowry, CO2 SO2 focused on lone electron pairs. HCl is accepting the lone pair Water is donating a pair of from the water. electrons to form a bond with the ( Arrows show the movement of electrons ) H atom. Which one is more basic ( H2O or NH3 )? NH3, because it has only one lone pair.  Acids Bases Taste sour ( Cause of taste in vinegar Taste bitter. and citric fruits ). Feel slippery ( React with skin oils to Essential to the chemical industry form slippery soaps ). ( Sulfuric acid is the number one Heavily used in industry, with sodium chemical produced in the United States ). hydroxide being the most common. Strong and Weak Acids and Bases Strength of an acid or a base : is the measure of how much remains after being added to water. - A strong acid or base will have little of the original chemical left. Hydrochloric acid (HCl) is a strong acid , all of it is converted to ions. - A weak acid or base will have a lot of the original chemical left. Acetic acid (C2H4O2) is a weak acid, much of the original chemical remains when added to water. The stronger the acid or base, the better it conducts electricity ( H2O < C2H4O2 < HCl ). Acids Dissociate = break Bases Strong acids give ( H+ ) easily. Strong bases give ( OH- ) easily. HCl > H2SO4 > H3PO4 > CH3COOH NaOH > Ca(OH)2 Corrosive ability is based on concentration, not the strength of an acid or a base. - Highly concentrated solutions tend to be more corrosive. - Less concentrated solutions tend to be less corrosive.  Neutralization Neutralization : A reaction between an acid and a base forms salt and water. Salts : Are ionic products of acid-base reactions. HCl + NaOH > NaCl + H2O NaCl is a common salt. HCl + KOH > KCl + H2O Amphoteric Amphoteric : A substance that can behave as an acid or a base ( Depends on what is paired with ). + - HF + HF H2F + F ( For every one hydroxide ion that forms there is one hydronium ion that forms ). The pH Scale -7 Pure water contains roughly 1 × 10 M H+ and OH– ions. The concentration of H3O+ ([H3O+]) multiplied by the concentration of OH– ([OH–]) always equals a constant Kw. -14 Kw = 1 x 10 + - H2O H + OH -14 -7 -7 1 x 10 1x10 + 1x10 pH scale : is used to describe acidity of a solution. + pH = - log [ H3O ] The power to which 10 is raised. 3 log 10 = 3  Types of solutions : Two common ways to determine pH : 1. pH Indicator Paper or Strips : red = acid, blue = base. 2. pH Meter. - + Whenever OH / H3O is written bigger, the solution becomes more acidic/basic. Buffer and conjugate acids and base pair Buffer solution : A solution that resists changes in pH upon the addition of an acid or a base. - Contains two components, each neutralizing an acid or a base. - Often prepared by mixing a weak acid and a salt of that weak acid. A strong acid added to the buffer is A strong base added to the buffer is neutralized by the base component ( = salt ). neutralized by the acid component ( = salt ). Blood contains several buffer systems. - Maintains pH between 7.35 and 7.45. - Outside this range, proteins become denatured. - One buffer system in the blood is based on the carbonic acid/sodium bicarbonate system.  Concept Check Identify the behavior as an acid or a base of each participant in the reaction : - + H2PO4 + H3O > H3PO4 + H2O H2PO4– gains a hydrogen ion to become H3PO4. In accepting the hydrogen ion, H2PO4– is behaving as a base. It gets the hydrogen ion from the H3O+, which is behaving as an acid. In the reverse direction, H3PO4 loses a hydrogen ion to become H2PO4– and is thus behaving as an acid. The recipient of the hydrogen ion is the H2O, which is behaving as a base as it transforms to H3O+. How is it possible for carbon dioxide, CO2, to behave as an acid when it has no hydrogen ions to donate? Carbon dioxide behaves as an acid when it accepts the lone pair on the oxygen atom of a water molecule. Is a neutralization reaction best described as a physical change or a chemical change? New chemicals are formed during a neutralization reaction, meaning the reaction is a chemical change. -7 In pure water, the hydroxide-ion concentration is 1.0 × 10 M. What is the hydronium-ion concentration? -7 1.0 × 10 M, because in pure water, [H3O+] = [OH–]. What is the concentration of hydronium ions in a solution if the concentration of hydroxide ions is -3 1.0 × 10 M? -11 -14 1.0 × 10 M, because [H3O+][OH–] must equal 1.0 × 10 = Kw. Complete the following questions : + -3 a- [ H ] = 1 x 10 M pH = 3 b- pH = 5 + -5 [ H ] = 1x10 M What is the pH of a neutral solution? + pH = - log [ H3O ] -7 = - log [ 10 ] = - ( -7 ) =7 How does adding ammonia, NH3, to water make a basic solution when there are no hydroxide ions in the formula for ammonia? Ammonia indirectly increases the hydroxide-ion concentration by reacting with water : + - NH3 + H2O > NH4 + OH This reaction raises the hydroxide-ion concentration, which has the effect of lowering the hydronium- ion concentration. With the hydroxide-ion concentration now higher than the hydronium-ion concentration, the solution is basic. Why do most buffer solutions contain two dissolved components? The weak base component neutralizes any incoming acid, and the weak acid component neutralizes any incoming base. How does adding an acid, such as HCl, cause a decrease in the concentration of hydroxide ions? HCl donates hydrogen ions (H+) to the solution. These hydrogen ions then react with hydroxide ions (OH-) present in the solution to form water (H2O). This reaction is known as neutralization. - - HCl + OH > H2O + Cl As a result of this reaction, the concentration of hydroxide ions decreases because they are being consumed in the neutralization process. How does adding a base, such as NaOH, cause a decrease in the concentration of hydronium ions? NaOH donates hydroxide ions (OH-) to the solution. These hydroxide ions then react with hydronium ions (H3O+) present in the solution to form water (H2O). This reaction is know as neutralization. + + NaOH + H3O > 2H2O + Na As a result of this reaction, the concentration of hydronium ions decreases because they are being consumed in the neutralization process.  Organic Compounds Chapter 12 Organic Chemistry Organic chemistry : is the branch of chemistry dealing with carbon containing compounds. Inorganic chemistry : is the branch of chemical that study about other elements. Q : Why we study only about C in organic chemistry? 1. Carbon valency is 4, so it can form 4 bonds with many other types of atoms. 2. The bond between carbon atoms is very strong and stable covalent bond. 3. Carbon can form single, double and triple bonds. 4. Unlimited carbon atoms can join to each other, so we can form unlimited number of compounds. Catenation : is the ability of chemical elements to bind to themselves and form long chains or rings. ( Because of the catenation, carbon can form strong covalent bonds, and unlimited carbon atoms can join to each other, such as plastic and diamond “ very strong “ ) Hydrocarbons Hydrocarbon : A compound containing only carbon and hydrogen atoms ( nonpolar). Examples : Mathane “ CH4 “, Ocatne “ C8H18 “, Polyethylene “ (C2H4)n”. Aliphatic Aromatic Open-chain or cyclic. Aroma ( smell ). Alkane Alkene Alkyne  Fossil fuel Hydrocarbons are obtained from coal and petroleum. - Formed from animal matter decaying in absence of air. - Petroleum forms various hydrocarbons through a C8H18 process called fractional distillation ( Includes tar, gasoline, and natural gas “ Methane “ ). - Molecular mass ∝ Boiling point, that is why methane is produced first. ( impure hydrocarbon ) Furnace ( 3000°C - 5000°C ) Effects of branching in gasoline : Octane rating : A measure of how well a hydrocarbon fuel burns relative to two standards. - High octane rating = a fuel that is more resistant to knocking. - The one with branch is better for car engines. Some hydrocarbons burn more efficiently than others in a car engine.  Aliphatic Alkane Alkene Alkyne Saturated hydrocarbon ( has Unsaturated hydrocarbon ( has Unsaturated hydrocarbon Definition 4 hydrogen atoms ) that has less than 4 hydrogen atoms ) that that has one or more triple only single covalent bonds has one or more double covalent covalent bond between between carbon atoms. bond between carbon atoms. carbon atoms. Formula CnH2n+2 CnH2n C nH 2n-2 Hydrocarbon’s root name + ane root name + ene root name + yne name ( Ethyne “ Acetylene “ is used for metal welding ) Alkyl group Alkyl group : is formed by removing a hydrogen atom from an alkane, and replacing the -ane with -yl. Formula : CnH 2n+1 Alkyl’s name : root name + yl  ‫‪Aromatic‬‬ ‫‪ Armoatic : Compounds containing one or more benzene ring.‬‬ ‫) ‪ Benzene : C6H6 ( An important alkene compound‬‬ ‫‪ Structure : Has three double bonds in a flat hexagonal ring.‬‬ ‫‪Naming Hydrocarbons‬‬ ‫‪ -١‬نحدد السلسلسة الرئيسة‪ ,‬ف حال وجود رابطة ثنائية‪/‬ث;ثية يجب أن تتضمنها السلسلة‪.‬‬ ‫‪Prefixes :‬‬ ‫‪ -٢‬نسمي السلسلة الرئيسة والتفرعات ا‪K‬انبية‪.‬‬ ‫‪2 = di‬‬ ‫‪ U‬مراعاة أن ذرة الكربون التي لديها‬ ‫‪ -٣‬نبدأ بترقيم السلسلة الرئيسة من أحد ا‪R‬طراف‪ ,‬يجب أو ً‬ ‫‪3 = tri‬‬ ‫رابطة ثنائية‪/‬ث;ثية يكون لديها الترقيم ا‪R‬صغر‪.‬بعد ذلك‪ ,‬نعطي ا‪R‬رقام الصغيرة للتفرعات‪ ,‬مع‬ ‫‪4= tetra‬‬ ‫‪ U‬ف الترتيب ا‪R‬بجدي‬ ‫محاولة إعطاء اسم التفرع الذي يبدأ بحرف يتواجد أو ً‬ ‫) ‪( dimethyl‬‬ ‫" ا‪hg‬ليزي " الرقم ا‪R‬صغر‪.‬‬ ‫ضا ف‬ ‫‪ -٤‬ف حال وجود نفس ا‪l‬موعة الفرعية أكثر من مرة نستخدم البادئات‪ ,‬ويتم استخدامها أي ً‬ ‫‪Put a prefix after the root name if‬‬ ‫حالة وجود أكثر من رابطة واحدة ثنائية‪/‬ث;ثية‪.‬‬ ‫‪there is more than one double/‬‬ ‫‪ -٥‬يتم كتابة ا‪U‬سم النهائي‪ ,‬مع استخدام ا‪R‬رقام ل‪q‬شارة إلى مواقع الروابط والتفرعات‪ ,‬والشرطات‬ ‫‪triple bond ( hexadiene ).‬‬ ‫للفصل بي الرقم وا‪U‬سم‪ ,‬والفواصل للفصل بي ا‪R‬رقام‪ ,‬والبدء بوضع اسم ا‪l‬موعة الفرعية التي‬ ‫‪ U‬ف الترتيب ا‪R‬بجدي " ا‪hg‬ليزي "‪.‬‬ ‫تبدأ بحرف يتواجد أو ً‬ ‫‪ -٦‬ف حالة وجود الهيدروكربون على شكل حلقة يتم وضع كلمة ‪ cyclo‬قبل اسم الهيدروكربون‪,‬‬ ‫واذا كانت ا|لقة حلقة بنزين فيتم وضع كلمة ‪ benzene‬ل‪q‬شارة إلى اسم الهيدروكربون‪.‬‬ ‫‪Cis and Trans‬‬ ‫‪ Double and triple bonds cannot freely rotate,‬‬ ‫‪leads to cis/trans isomerism.‬‬ ‫‪ Cis : the bulk ( bigger molecular mass ) of the‬‬ ‫‪carbons are on the same side of the double bond.‬‬ ‫‪ Trans : the bulk of the carbons are on opposite‬‬ ‫‪sides of the double bond.‬‬  Configuration and structural isomers The specific way in which the atoms of a molecule are connected to one another # of carbons # of isomers Configuration ( Connectivity) : The way atoms are bonded to one another. 5 3 Structural isomers : Two molecules with the same formula and 6 5 same molecular mass but different configurations ( structures ), 7 9 so each exhibits different properties due to the differences. 8 18 10 75 Space-filling model 2D rendition Stick structure : Bonds and atoms are represented by using Iso is used when one Neo is used when sticks or lines. methyl group is two methyl groups attached to the 2nd are attached to the carbon atom. 2nd carbon atom. Conformations Conformations : Different spatial orientations of a single configuration ( rotation of bond). - Atomic bonding does not change however. ! Functional Groups Give Organic Compounds Character Heteroatom : An atom other than carbon and hydrogen in organic chemistry ( N, O, Cl, Br, I ). - Attaches to the hydrocarbon backbone of the compound. – Has profound effects on the overall properties of the compound. Functional group : A combination of atoms that behaves as a unit ( R-functional group, R = hydrocarbons ). - Most are distinguished by the heteroatoms they contain. 1 Alcohols Organic molecules containing a hydroxyl group (R–OH). - Small alcohols can be very polar overall and acidic because of the hydrogen “ according to the Arrhenius theory”. Methanol ( CH3OH ) : Used in production of plastics and as a solvent, known as wood alcohol and can be deadly if ingested ( not for drink ). Ethanol ( C2H5OH ) : The “alcohol” in alcoholic beverages, produced by fermentation ( for drink ). 2 Phenols A compound with a hydroxyl group attached to a benzene ring ( benzene ring-OH ). - Can act as an acid lose the H of the hydroxyl group, it is more acidic than alcohol because of the benzene ring, and it becomes more stable when we remove H. 4-n-hexylresorcinol Thymol 3 Ethers A compound with oxygen bound to two separate carbon atoms ( R-O-R ). - Not readily soluble in water. - Diethyl ether was used as an anesthetic historically. - Has very low boiling point. CH3-O-CH3 < CH3CH2OH ( “ in boiling point “ because ethanol is acidic. They have the same molecular mass, but the structure is different ). 3 Amines Organic compounds that a nitrogen atom is bound to one or more saturated carbon atoms ( R-N ). - Less soluble in water than alcohols. - Often have an offensive odor ( bad smell ). - Amines are weak bases. - Found often as alkaloids, they accept H+ ions ( Alkaloids naturally occurring compound , can be found in plants such as coffee and tea “ because of amines, our teeth become yellowish after drinking them “). - Normally found as tannins in nature ( Tannins are salts of alkaloids ). Carbonyl group : Contains a carbon double bond to an oxygen atom ( C = O ). - Present in ketones, aldehydes, amides, carboxylic acids, and esters. 4 Ketone O A molecule where the carbonyl carbon is bound to two other carbon atoms ( R-C-R ). Acetone : Is often used in fingernail polish remover and painting walls. 5 Aldehyde O When the carbonyl carbon is bound to a carbon and a hydrogen or two hydrogen atoms ( R-C-H ). - Often are the sources of simple smells. Acetaldehyde Formaldehyde 6 Amide O Compound in which the carbonyl carbon is bound to a nitrogen atom ( R-C-N ). DEET : A mosquito repellent. 7 Carboxylic acid O When the carbonyl carbon is attached to a hydroxyl group ( R-C-OH ). - The hydroxyl H atom is an acidic hydrogen, so they are slightly acidic. C2H4O2 : the main ingredient in vinegar. Acetylsalicylic acid ( Aspirin ) 8 Ester O An organic molecule similar to a carboxylic acid but the H is replaced with a carbon ( R-C-OR ). - Used for flavour. Methyl salicylate Penicillin ( Wintergreen )  Concept Check Which carbon–carbon bond was rotated to go from the “before” conformation of isopentane to the “after” conformation? Bond c is the bond that rotated. Where do hydrocarbons come from? Fossil fuels. Do the heavier or the lighter molecules of crude oil rise to the top of the fractionation tower? The lighter molecules found in crude oil rise highest within the fractionation tower. These molecules have the lower boiling points. So the lower the boiling point is, the higher the molecules rise. Name the following hydrocarbons chain : Butane 2-Butene Neohexane 2,4-dimethyl hexane 3-methyl hexane What is the significance of heteroatoms in an organic molecule? Heteroatoms largely determine an organic molecule’s physical and chemical properties.