Supplemental Instruction
IowaStateUniversity / Leader: / Lillian Howard
Course: / Chem 178 (B)
Instructor: / Dr. Burnett
Date: / 4/4/13
- T/F A reaction that is spontaneous in the forward reaction only, is an irreversible reaction.
- T/F According to the 3rd Law of Thermodynamics, the entropy of any crystalline solid at absolute zero is 0.
- Which has more entropy? Explain.
- F2 or Cl2
- CO2 (s) or CO2(g)
- A crystal of pure Mg at 0 K or a crystal at 200 K
- For each of the following changes, predict whether ΔS is greater or less than 0.
- Sugar + water sugar water
- Na2SO4(s) 2Na + (aq) + SO42-(aq)
- 2H2(g) + O2(g) 2H2O (g)
- Calculate entropy change when 36.0 g of ice melts at 273 K and 1 atm.
Molar enthalpy = 6.01 kJ/mol.
- a. When KNO3 is cooled from 30˚C to 5˚C, what is the expected sign of ΔS?
b. Explain the sign of ΔS in terms of changes at the molecular level.
- Calculate the entropy change for the following reaction at 25˚C.
2SO2(g) + O2(g) 2SO3(g)
Given: S˚(SO2) = 248.5 J/K mol
S˚(O2) = 205.0 J/K mol
S˚(SO3) = 256.2 J/K mol
- In an acid solution, the mechanism for the reactionNH4++ HNO2 N2+ 2 H2O + H+is:
- HNO2 + H+ H2O + NO+
- NH4+ NH3 + H+
- NO+ + NH3 NH3NO+ Slow step
- NH3NO+ H2O + H+ + N2
- Derive the rate law
- (Review)Given the energy-profile diagram, which of the following statements could be true:
- an exothermic reaction
- an endothermic reaction
- a reaction with two steps in its reaction mechanism
- a reaction with three steps in its reaction mechanism
- a catalyzed reaction involving two successive steps
- spontaneous
- non-spontaneous
- (Looking Forward)Calculate ΔS for the reaction: 4CuO(g) 2Cu2O(s) + O2(g) at 298 K given the equation ΔG = ΔH - TΔS:
- ΔH(CuO) = -157.3 kJ/mol
- ΔH(Cu2O)= -168.6 kJ/mol
- ΔG(CuO) = -129.7 kJ/mol
- ΔG(Cu2O)= -146.0 kJ/mol
- Is this reaction feasible for the preparation of Cu2O(s) at standard conditions?
- If not, how could it be made to occur?