Final answer:
The standard enthalpy of reaction for the neutralization of HCl with NaOH is exothermic, releasing 56 kJ per mole of reactants.
Step-by-step explanation:
The standard enthalpy of reaction for the neutralization of hydrochloric acid (HCl) with sodium hydroxide (NaOH) to form sodium chloride (NaCl) and water (H2O) is an exothermic process. This means that as HCl (aq) reacts with NaOH (aq) to produce NaCl (aq) and H2O (l), energy is released into the surroundings, typically as heat.
The given enthalpy change (ΔH) for this reaction is -56 kJ per mole, indicating that 56 kJ of heat is released for every mole of HCl and NaOH that react. In calorimetry experiments, as when the temperature of the solution rises from one temperature to another, it confirms the exothermic nature of the reaction.
This temperature rise is a direct result of the heat released during the reaction. Therefore, the answer to the question is (a) Exothermic.