Question

When crystalline solid barium hydroxide octahydrate and crystalline solid ammonium nitrate are mixed in a beaker at room temperature, a spontaneous reaction occurs. The temperature of the beaker contents rapidly falls to below 0°C. Use this information to decide whether the reaction is exothermic or endothermic and what the signs of ΔH and ΔS are. A) endothermic; ΔH > 0;Δ S > 0 B) exothermic; ΔH < 0;Δ S > 0 C) endothermic; ΔH < 0;Δ S < 0 D) endothermic; ΔH < 0;Δ S > 0 E) exothermic; ΔH > 0;Δ S < 0

Answer 1

Answer:

A) endothermic; ΔH > 0;Δ S > 0

Explanation:

Since temperature falls => system absorbs heat

=> reaction is endothermic

Since reaction is endothermic => Delta H is positive (+)

Since reaction is spontaneous, Delta G = Delta H - T x Delta S is negative

Since Delta G is negative, Delta H is positive and T is positive

=> Delta S is positive (+)