1. Answer the following questions: a) can Al3+(aq) oxidize tin (Sn) under standard-state conditions?; b) would it be OK to store an aqueous AlCl3 solution in a tin container?; c) can Sn2+(aq) oxidize aluminum (Al) under standard state conditions?; d) would it be OK to store an aquous SnCl2 solution in an aluminum container?

A. a) yes; b) yes; c) no; d) no
B. a) no; b) no; c) yes; d) yes
C. a) yes; b) no; c) no; d) yes
D. a) no; b) yes; c) yes; d) no

2. The exothermic reaction NH3(g) + HCl(g) ? NH4Cl(s) proceeds spontaneously at 25°C even though there is a decrease in disorder in the system (gases producing a solid). Why?

A. the exothermic reaction increases the temperature from 25°C to a higher temperature which increases the T?S component
B. there is a phase change from gases to solid which means ?G is zero which, when combined with a negative ?H, results in a spontaneous process
C. the decrease in entropy of the system is offset by an increase in the entropy of the surroundings caused by the absorption of heat by the system from the surroundings
D. the decrease in entropy of the system is offset by an increase in the entropy of the surroundings caused by the release of heat from the system to the surroundings

3. The equilibrium reaction CaCO3(s) ? CaO(s) + CO2(g) reaches ?G° = 0 at 835°C. At this temperature:

A. ?H° = ?S°
B. the percent yield of CaO reaches 100%
C. the reaction becomes exothermic
D. the pressure of CO2 is 1 atm
E. the decomposition of CaCO3 begins