(a) The energy cycle shown can be used, along with suitable data, to calculate the enthalpy change of hydration of Ca²⁺(g).
Each arrow indicates a transformation, W, X, Y and Z. Each transformation consists of one or more steps.
[Figure 3.1]
The following data and data from the Data Booklet should be used.
electron affinity of Cl(g) = -349 kJ mol-1
enthalpy change of atomisation of Ca(s) = +193 kJ mol-1
enthalpy change of formation of CaCl₂(s) = −795kJ mol-1
enthalpy change of solution of CaCl2(s) = -83 kJ mol-1
enthalpy change of hydration of Cl-(g) = -364 kJ mol-1

Q: What topic does this question test?

This question tests Chemical energetics in A-Level Chemistry (syllabus code 9701). It is worth 13 marks.

Q: Which exam paper is this question from?

This question appeared in the Cambridge A-Level Chemistry Oct/Nov 2020 examination, Paper 4 Variant 2 (9701_w20_qp_42.pdf).

Question

(a) The energy cycle shown can be used, along with suitable data, to calculate the enthalpy change of hydration of Ca²⁺(g).
Each arrow indicates a transformation, W, X, Y and Z. Each transformation consists of one or more steps.
[Figure 3.1]
The following data and data from the Data Booklet should be used.
electron affinity of Cl(g)                    = -349 kJ mol-1
enthalpy change of atomisation of Ca(s)       = +193 kJ mol-1
enthalpy change of formation of CaCl₂(s)      = −795kJ mol-1
enthalpy change of solution of CaCl2(s)       = -83 kJ mol-1
enthalpy change of hydration of Cl-(g)        = -364 kJ mol-1

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