Sodium reacts violently with water according to the equation: 2 Na(s) + 2 H₂O(l) → 2 NaOH(aq) + H₂(g)
The resulting solution has a higher temperature than the water prior to the addition of sodium.What are the signs of ΔH° and ΔS° for this reaction?

Question

Quizplus · Accepted Answer

The reaction is exothermic since the resulting solution has a higher temperature than the water. This means that ΔH° is negative. 
The reaction involves the conversion of solid sodium and liquid water into aqueous solution and gaseous hydrogen gas. This implies that the reactants have lower entropy than the products since the number of molecules increases. Therefore, ΔS° is positive.
Thus, the best choice is B, where ΔH° is negative and ΔS° is positive.

Sodium Reacts Violently with Water According to the Equation: 2