A laboratory route for preparing aqueous calcium chloride involves reacting solid calcium carbonate with hydrochloric acid, followed by dissolving the gaseous carbon dioxide produced. The simplified sequence at 298 K is described below.
Assume that the aqueous solutions are sufficiently dilute to treat them as ideal.
(a) Write the overall balanced chemical equation for producing CaCl₂(aq) with dissolved CO₂ starting from CaCO₃(s) and HCl(aq).
(b) Calculate the overall enthalpy change (in kJ mol⁻¹ of CaCl₂ produced) for the two-step sequence.
(c) Explain qualitatively how the dissolution of CO₂ affects the net enthalpy change compared with releasing CO₂ as a gas.