The enthalpy change for KOH(aq) + HNO 3 (aq) → KNO 3 (aq) + H 2 O(l) is -57.3 kJ. Predict the enthalpy change for: Ca(OH) 2 (aq) + H 2 SO 4 (aq) → CaSO 4 (s) + 2H 2 O(l)

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TestHub · Accepted Answer

Two moles of water form, contributing 2 × (-57.3) = -114.6 kJ. Additionally CaSO 4 precipitates (sparingly soluble), and precipitation is exothermic, so the true value must be more negative than -114.6 kJ. Only -130.2 kJ qualifies, option (d).

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