Question

Trevor dissolves sodium hydroxide pellets in a beaker of water at room temperature, and notes that the beaker becomes warm. Which correctly designates the signs of Delta.H, Delta.S, and Delta.G for this process?
Delta.H > 0, Delta.S > 0, and Delta.G < 0
Delta.H < 0, Delta.S > 0, and Delta.G < 0
Delta.H > 0, Delta.S > 0, and Delta.G > 0
Delta.H < 0, Delta.S < 0, and Delta.G > 0

Answer 1

Delta.H < 0, Delta.S > 0, and Delta.G < 0.

Reason: Dissolving NaOH releases heat (beaker warms) so the enthalpy change is negative (exothermic). The solid dissociates into many mobile ions, increasing disorder so ΔS > 0. Both effects make dissolution spontaneous at room temperature, so ΔG < 0.