Download Exam 2 Study Guide - General Chemistry | CHM 122 and more Study notes Chemistry in PDF only on Docsity! Practice Problems EXAM 2 Question I: Multiple Choices 1. Which thermodynamic function is most related to disorder and probability? a. Enthalpy b. Internal energy c. Entropy d. Heat capacity 2. For the process of freezing liquid ethanol at a given temperature and pressure a. ΔH is negative and ΔS is negativeH is negative and ΔH is negative and ΔS is negativeS is negative b. ΔH is negative and ΔS is negativeH is negative and ΔH is negative and ΔS is negativeS is positive c. ΔH is negative and ΔS is negativeH is positive and ΔH is negative and ΔS is negativeS is negative d. ΔH is negative and ΔS is negativeH is positive and ΔH is negative and ΔS is negativeS is positive 3. A process is carried out at constant pressure. Given that ΔH is negative and ΔS is negativeE is positive and ΔH is negative and ΔS is negativeH is negative a. The system absorbs heat and expands during the process b. The system absorbs heat and contracts during the process c. The system loses heat and expands during the process d. The system loses heat and contracts during the process 4. Which of the following is not a state function? a. Altitude b. Heat c. Internal energy d. Volume 5. For which of the following process will the entropy increases? a. Condensation of steam b. Reaction of magnesium with oxygen to form magnesium oxide c. Reaction of nitrogen and hydrogen to form ammonia gas d. Sublimation of dry ice 6. What is the approximate value of the equilibrium constant, Kn, for the neutralization of pyridine with hydrochloric acid, shown in the equation below? The Kb for pyridine is 1.8 × 10–9. HCl(aq) + C5H5N(aq) ⇌ C5H5NHCl(aq) A) 5.6 × 10-10 B) 5.6 × 10-6 C) 1.8 × 105 D) 5.6 × 108 7. Indicate the major chemical species present in a solution of 0.10 M NH3 and 0.10 M NH4Cl. A) NH3, NH4+ B) NH3, NH4+, Cl- C) NH3, NH4+, Cl-, OH- D) NH3, NH4+, Cl-, OH-, H2O 1 Question II.Buffers 1) What is the pH of a 150.0 ml buffer of 0.10 M Na2HPO4/0.15 KH2PO4? Do not use Henderson Hassalbalch equation. (Hint: is this a monoprotic or polyprotic acid? Which Ka should be used in this problem?) What is the new pH of the buffer after adding 10.5 ml of 0.10M KOH. Assume the volume is additive). Neutralization reaction must be shown and you can use Henderson Hassalbalch to solve for the new pH 2) A solution is prepared by dissolving 0.535 g of NH4Cl in 250.0 ml of 0.080 M NH3. 2
