Spontaneity — Prelims Questions

For a certain reaction, $\Delta H = -30,\text{kJ/mol}$ and $\Delta S = -50,\text{J/mol·K}$. At what temperature range will the reaction be spontaneous?

Which of the following conditions will always result in a spontaneous reaction?

For the reaction $2A(g) + B(g) \rightleftharpoons 2C(g)$, at $298,\text{K}$, $\Delta H^circ = -100,\text{kJ}$ and $\Delta S^circ = -200,\text{J/K}$. Calculate $\Delta G^circ$ for the reaction at $298,\text{K}$ and predict its spontaneity.

Which of the following statements is INCORRECT regarding spontaneity?

For a reaction, $\Delta G^circ = -20,\text{kJ/mol}$ at $298,\text{K}$. Calculate the equilibrium constant ($K$) for this reaction. (Given: $R = 8.314,\text{J/mol·K}$)

Consider the phase transition: $H_2O(l) \rightleftharpoons H_2O(s)$. This process is spontaneous at $263,\text{K}$ but non-spontaneous at $283,\text{K}$. What are the likely signs of $\Delta H$ and $\Delta S$ for the forward process (freezing)?