Consider the following endothermic reaction of gaseous AB3 molecules with A2 molecules (LO 9.16, 9.17). Identify the true statement about the spontaneity of the reaction. (a) The reaction is likely to be spontaneous at high temperatures. (b) The reaction is likely to be spontaneous at low temperatures. (c) The reaction is always spontaneous. (d) The reaction is never spontaneous.

Verified step by step guidance

1. Step 1: Understand that the reaction is endothermic, meaning it absorbs heat from the surroundings. This implies that the enthalpy change (ΔH) is positive.
2. Step 2: Recall that the spontaneity of a reaction is determined by the Gibbs free energy change (ΔG), which is given by the equation ΔG = ΔH - TΔS, where T is the temperature and ΔS is the change in entropy.
3. Step 3: Consider the effect of temperature on ΔG. For an endothermic reaction (positive ΔH), increasing the temperature can make the TΔS term larger, potentially making ΔG negative if ΔS is positive.
4. Step 4: Analyze the entropy change (ΔS). If the reaction results in an increase in disorder (positive ΔS), then higher temperatures will favor spontaneity because the TΔS term will become more significant.
5. Step 5: Conclude that for an endothermic reaction with a positive ΔS, the reaction is more likely to be spontaneous at high temperatures, making option (a) the true statement.