Enthalpies of Solution & Hydration (Cambridge (CIE) A Level Chemistry): Exam Questions

i) Define the term standard enthalpy change of hydration in relation to the fluoride ion.

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ii) State whether the standard enthalpy change of hydration of the fluoride ion is an exothermic or endothermic process. Explain your answer.

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The standard enthalpy changes of hydration of the fluoride and chloride ions are −524 kJ mol^– and −364 kJ mol^– respectively.

Explain why the standard enthalpy change of hydration of the fluoride ion is more exothermic than that of the chloride ion.

Use the data in Table 2.1 to explain why the standard enthalpy change of hydration of the calcium ion is more exothermic than that of the sodium ion.

Table 2.1

Describe, in terms of electron transfer, the formation of solid calcium bromide, CaBr₂, from its atoms.

Table 3.1 gives thermodynamic data for calcium bromide, CaBr₂.

i) Define the term lattice energy.

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Table 3.1

ii) Using Table 3.1, calculate the standard enthalpy change of hydration of the calcium ion. Show your working.

enthalpy change of hydration of Ca²⁺ = ........................ kJ mol^–1

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Use the data in Table 3.2 to calculate the standard enthalpy change of solution of potassium fluoride. Show your working.

Table 3.2