• Question 01:

    Photosynthesis is a chemical reaction that occurs in nature, but one that is generally not thermodynamically favored. It is forced forward by the presence of light. Which of the following is another example of a thermodynamically unfavored process, which must be forced to occur by the use of an external source of energy?

  • Question 02:

    Which of the following combinations of conditions is found to be thermodynamically favored at high temperatures, but unfavored at low temperatures?

  • Question 03:

    Which of the following chemical reactions has a positive ΔS°?

  • Question 04:

    What is true of the absolute entropy values, S°, of all substances?

  • Question 05:

    Given the absolute entropies below, all given in units of J K-1 mol-1, calculate ΔS° for the formation of NH3(g) from its elements.

    S° N2(g) = 192
    S° H2(g) = 131
    S° NH3(g) = 193

    N2(g) + 3H2(g) → 2NH3(g)

  • Question 06:

    Which situation described below, is the one with the greatest entropy?

  • Question 07:

    Which combination of ΔG°, K and rate of reaction, best describes a thermodynamically favored reaction?

  • Question 08:

    Sodium nitrate is observed to be highly soluble in water under standard conditions. It is also observed that the temperature of the solution drops quite dramatically during the solution process. Which statement best describes these observations and the change in entropy that occurs?

  • Question 09:

    It is found that the reaction below has ΔG° = -35 kJ mol-1 and ΔH° = -100 kJ mol-1.

    A2(g) + 3B2(g) ⇌ 2AB3(g)

    It is also found that when reactants A2(g) and B2(g) are mixed in the stoichiometric ratio under standard conditions, no AB3(g) is formed. What is the best explanation for this observation?

  • Question 10:

    The combustion of a solid hydrocarbon in oxygen, leads to the production of two gases and the evolution of energy. The reaction is found to be thermodynamically favored. What is the driving force for this reaction?