Chemistry Exam: Solubility, Equilibria, and Thermodynamics - Prof. Eric Glendening, Exams of Chemistry

Download Chemistry Exam: Solubility, Equilibria, and Thermodynamics - Prof. Eric Glendening and more Exams Chemistry in PDF only on Docsity! Name ______________________________________ Chem 106 April 20, 2007 Fourth Hour Exam Potentially Useful Information: R = 0.08206 L atm/mol K = 8.314 J/mol K QRTGG ln0 +∆=∆ STHG ∆−∆=∆ KRTG ln0 −=∆ R S TR HK 00 1ln ∆+⎟ ⎠ ⎞ ⎜ ⎝ ⎛∆−= 1. (8 pts) Consider the following compounds. (i) Circle the compound that has the highest solubility in water. (ii) Cross out the compound that has the lowest solubility. MgF2 (Ksp = 6.4×10 –9) CaSO4 (Ksp = 6.1×10 –5) AgOH (Ksp = 2.0×10 –8) PbBr2 (Ksp = 4.6×10 –6) 2. (8 pts) Calculate the molar solubility of BaF2 (Ksp = 1.7×10 –6) in a solution containing 0.10 M NaF. molar solubility = ___________ 3. (8 pts) Explain, using balanced chemical equations, how the solubility of limestone (CaCO3) is influenced by acid solutions. (No calculations here!) 2 4. (8 pts) What is the minimum concentration of F– required to ensure that the concentration of Pb2+ remains below 1.0×10–6 M in a water sample? (Ksp = 3.6×10–8 for PbF2.) [F–] = ___________ 5. (18 pts) ∆G0 is 2.60 kJ/mol for the reaction H2(g) + I2(g) 2 HI(g) at 298 K. (a) Calculate the free energy of formation (∆Gf 0) for HI(g) at 298 K. ∆Gf 0 = ___________ (b) Calculate KP at 298 K. KP = ___________ (c) Calculate ∆G at 298 K when the partial pressures of H2, I2, and HI are 1.00, 0.75, and 0.50 atm, respectively. ∆G = ___________ (d) Is this reaction, given the initial conditions of part (c), spontaneous or non-spontaneous? In what direction does the reaction proceed? (e) Is this reaction spontaneous under standard conditions? (f) What is ∆G at equilibrium? ∆G = ___________