Calcium chloride, $\text{CaCl}_2$, is an ionic solid. The values of some energy changes are shown in Table 1.1. Table 1.1 energy change value / $\text{kJ mol}^{-1}$ --- --- lattice energy, $\Delta H^{\ominus}_{\text{latt}}$, $\text{CaCl}_2(\text{s})$ $-2237$ standard enthalpy change of atomisation of calcium $+193$ first ionisation energy of calcium $+590$ second ionisation energy of calcium $+1150$ standard enthalpy change of atomisation of chlorine $+121$ first electron…

Chemistry 9701/42 — October/November 2022

Cambridge A-Level · A Level Structured Questions · worked solutions for every part, with the mark scheme

questions

100

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120

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Topics Transition Elements · Carboxylic Acids and Derivatives · Hydrocarbons · Nitrogen Compounds · Hydroxy Compounds · Analytical Techniques · +6 more

Q1Chemical EnergeticsFree sample

Calcium chloride, $\text{CaCl}_2$ , is an ionic solid.

The values of some energy changes are shown in Table 1.1.

Table 1.1

energy change	value / $\text{kJ mol}^{-1}$
lattice energy, $\Delta H^{\ominus}_{\text{latt}}$ , $\text{CaCl}_2(\text{s})$	$-2237$
standard enthalpy change of atomisation of calcium	$+193$
first ionisation energy of calcium	$+590$
second ionisation energy of calcium	$+1150$
standard enthalpy change of atomisation of chlorine	$+121$
first electron affinity of chlorine	$-364$

(a)

Define lattice energy.

(b)

Use the data in Table 1.1 to calculate the standard enthalpy change of formation, $\Delta H^{\ominus}_f$ , of calcium chloride. It may be helpful to draw an energy cycle. Show all your working.

$\Delta H^{\ominus}_f(\text{CaCl}_2(\text{s})) = \text{.............................. } \text{kJ mol}^{-1}$

(c)

Three possible values for the first electron affinity of bromine are shown in Table 1.2. One of them is correct.

Place a tick by the correct value. Explain your choice.

Table 1.2

possible values	place one tick ( $\checkmark$ ) in this column
$-342 \text{ kJ mol}^{-1}$
$-364 \text{ kJ mol}^{-1}$
$-386 \text{ kJ mol}^{-1}$

explanation ................................................................................................................................

(d)

The enthalpy change of hydration of the chloride ion can be calculated using the lattice energy of calcium chloride and the data shown in Table 1.3.

Table 1.3

energy change	value / $\text{kJ mol}^{-1}$
standard enthalpy change of solution of $\text{CaCl}_2(\text{s})$	$-83$
standard enthalpy change of hydration of $\text{Ca}^{2+}(\text{g})$	$-1650$

(i)

Define the following terms.

enthalpy change of solution ................................................................................................

enthalpy change of hydration ................................................................................................

(ii)

Calculate the standard enthalpy change of hydration of the chloride ion, $\text{Cl}^-(\text{g})$ . It may be helpful to draw an energy cycle. Show all your working.

$\Delta H^{\ominus}_{\text{hyd}}(\text{Cl}^-(\text{g})) = \text{.............................. } \text{kJ mol}^{-1}$

(e)

Calcium fluoride, $\text{CaF}_2(\text{s})$ , can be synthesised directly from its elements.

The value of $\Delta H^{\ominus}_f(\text{CaF}_2(\text{s}))$ is $-1214 \text{ kJ mol}^{-1}$ .

(i)

Predict the sign of the entropy change, $\Delta S^{\ominus}$ , for this synthesis. Explain your answer.

The sign of the entropy change is .............................. .

explanation ................................................................................................................................

(ii)

Use the value of $\Delta H^{\ominus}_f(\text{CaF}_2(\text{s}))$ given in (e) and your answer to (e)(i) to predict how the feasibility for this synthesis will change with increasing temperature.

The rest of this paper

8 more questions

Q2Reaction Kinetics10M
Q3Electrochemistry11M
Q4Equilibria9M
Q5Transition Elements · Group 216M
Q6Transition Elements8M
Q7Carboxylic Acids and Derivatives · Hydrocarbons · Nitrogen Compounds · Hydroxy Compounds15M
Q8Introduction to A Level Organic Chemistry · Analytical Techniques10M
Q9Nitrogen Compounds · Carboxylic Acids and Derivatives · Hydrocarbons · Hydroxy Compounds · Analytical Techniques10M

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