Exam #4: Learning Module #4

Chemistry 1310 - Exam #4: Learning Module #4 or Chapters 11-13 Exam is Wednesday, December 1, 2021 at 8:00 am (on campus) NOTE: The following formulas and mathematical relationships that WILL NOT be given to you on the exam and that you will need to know are: • • • • • • • • Kp = Kc x (RT)n pH = - log [H3O+] & pOH = - log [OH-] 10-pH & 10-pOH pKa = - log Ka, pKb = - log Kb & pKw = - log Kw 10-pka , 10--pKb & 10-pKw 14 = pH + pOH Ka x Kb = Kw The Hess’ Law Equation for Enthalpy (H), Entropy (S) or Gibbs Free Energy (G) The following WILL be given to you on the exam: • • • • Suniverse = So + Ssurroundings Ssurroundings = -(Ho/T) Go = - RTlnK & Go reaction = Ho - TSo  G= Go + RTlnQ pH = pKa + log (Base)/Acid) • o • • • Ecell = oEcathode + oEanode & E = oEcell – (RT/nF) lnQ Go = - nFoEcell All constants English to metric conversions, except for 1 inch = 2.54 cm or 1 mL = 1 cm3 1. Equilibrium a. Write equilibrium expressions from balanced chemical equations; both homogeneous and heterogeneous reactions. b. Derive equilibrium constant value when given other equilibrium constants. c. Describe what the numerical value of K indicates about a reaction (i.e. K>1 product favored, etc.) d. Solve for K constant value if given equilibrium concentration of reactants and products. e. Using ICE solve for equilibrium concentrations of reactants and products when given initial concentrations of reactants. f. Describe Q and solve Q problems g. Describe the Le Châtelier’s Principle & determine how a reaction at equilibrium shifts when conditions are changed. 2. Acid/Base Chemistry a. Define acid and base according to Brönsted- Lowery definition and Lewis Acid Base Theory. b. Distinguish between a strong acid vs. a weak acid; or a strong base vs. a weak base. c. Recognize conjugate acid-base pairs d. Define amphoterism and the leveling effect. e. Calculate pH or pOH for strong acids and bases. f. Calculate the [H3O+] or [OH-] if given their pH or pOH respectively. g. Derive Ka or Kb using Ka x Kb = Kw h. Calculate pH for weak acids and weak bases using ICE i. Identify, qualitatively, whether a salt is neutral, acidic or basic. j. Determine the pH of a salt solution, quantitatively. 3. Aqueous Equilibria a. Describe a buffer solution and define buffer capacity & buffer limits. b. Select conjugate acid- base pairs to make a buffer at a specific pH when given pKa or pKb values. c. Calculate the pH of a buffer solution using either ICE or the Henderson-Hasselbalch equation. d. Define Ksp and write a Ksp expression. e. Calculate Ksp value when given molar solubilities. f. Calculate molar solubilities if given Ksp value. g. Predict where the solution is saturated, unsaturated or super saturated based on Q sp vs. Ksp comparisons. h. Describe how the common ion effect influences the molar solubilities. 4. Thermodynamics II a. Describe the three Laws of Thermodynamics b. Predict spontaneity when given various situations. c. Calculate standard entropy of a reaction or a product or a reactant using Thermodynamic tables. d. Calculate the entropy of the surroundings knowing the enthalpy of the reaction. e. Calculate the entropy of the universe. f. Define Gibbs free energy. g. Describe what the sign of delta G means about a reaction’s spontaneity. h. Calculate Gibbs free energy using values from Thermodynamic tables. i. Calculate Gibbs free energy indirectly from other chemical reactions and their delta G values. j. Calculate Gibbs free energy from delta H and delta S values. k. Describe the relationship between Gibbs Free energy and Equilibrium & calculate delta G from its equilibrium constant. l. Calculate the equilibrium constant value given delta G. m. Determine Gibbs free energy under nonstandard conditions. 5. Redox & Electrochemistry a. Balance redox equations in neutral, acidic or basic environments b. Calculate cell potentials under standard conditions using Reduction Potential Tables. c. Write a balanced redox reaction for a electrochemical cell from a short-hand notation. d. Distinguish between a galvanic (e.g. voltaic or Daniel cell) and an electrolytic electrochemical cell. e. Describe the various parts (i.e. anode, cathode, salt bridge, flow of electrons etc.) for an electrochemical cell. f. Use the Nernst Equation to calculate cell potential and Q at nonstandard conditions.