Question

question 10 (4 points)
the second law of thermodynamics states that _________.
○ a) δe = q + w
○ b) δh°rxn = σ nδh°f (products) - σ mδh°f (reactants)
○ c) for any spontaneous process, the entropy of the universe increases
○ d) the entropy of a pure crystalline substance is zero at absolute zero

Explanation:

• Option a: $\Delta E = q + w$ is the first law of thermodynamics (relates internal energy change to heat and work), not the second law.
• Option b: The formula for calculating standard enthalpy of reaction ($\Delta H^{\circ}_{rxn}=\sum n\Delta H^{\circ}_{f}(\text{products}) - \sum m\Delta H^{\circ}_{f}(\text{reactants})$) is about enthalpy calculations, not the second law.
• Option c: The second law of thermodynamics (in terms of entropy) states that for any spontaneous process, the entropy of the universe (system + surroundings) increases. This matches the description.
• Option d: The statement about entropy of a pure crystalline substance being zero at absolute zero is the third law of thermodynamics.

Answer:

c) for any spontaneous process, the entropy of the universe increases