[Maximum number: 4]

Potassium chloride, KCl , and magnesium chloride, $\mathrm{MgCl}_{2}$ , are both ionic solids.

Table 1.1

(a)

Explain the reasons why the lattice energy of $\mathrm{MgCl}_{2}$ is more exothermic than the lattice energy of KCl.

[ 2 ]

(b)

Define the following terms.

[ 2 ]

(i)

enthalpy change of atomisation

[ 1 ]

(ii)

first electron affinity

[ 1 ]

(a)

(i)

Use the data in the table below, and relevant data from the Data Booklet, to calculate the lattice energy, $\Delta H_{\text {latt }}^{\ominus}$ , of potassium oxide, $\mathrm{K}_{2} \mathrm{O}(\mathrm{s})$ .

\Delta H_{\text {latt }}^{\ominus}=\ldots \ldots \ldots \ldots \ldots \ldots \ldots . . . . . . . . . . . . . . k J ~ \mathrm{~mol}^{-1}

[ 3 ]

(ii)

State whether the lattice energy of $\mathrm{Na}_{2} \mathrm{O}$ would be more negative, less negative or the same as that of $\mathrm{K}_{2} \mathrm{O}$ . Give reasons for your answer.

[ 1 ]

(a)

(i)

Define lattice energy.

[ 2 ]

(ii)

The lattice energy of the Group 2 carbonates, $\Delta H_{\text {latt }}^{\theta}\left(\mathrm{MCO}_{3}\right)$ , becomes less exothermic down the group.

The lattice energy of the Group 2 oxides, $\Delta H_{\text {latt }}^{\theta}(\mathrm{MO})$ , also becomes less exothermic down the group.
$\Delta H_{\text {latt }}^{\theta}\left(\mathrm{MCO}_{3}\right)$ and $\Delta H_{\text {latt }}^{\theta}(\mathrm{MO})$ change by different amounts going down the group.
Suggest how the standard enthalpy change of the decomposition reaction for Group 2 carbonates changes down the group.

Explain your reasoning in terms of the relative sizes of the anions and the relative changes in lattice energy down the group.

[ 2 ]

[Maximum number: 5]

paper chromatography,

(a)

Strontium chloride, $\mathrm{SrCl}_{2}$ , can be used to produce a red colour in fireworks.

[ 5 ]

(i)

Use the following data, together with relevant data from the Data Booklet, to calculate a value for the lattice energy of strontium chloride. You may find it helpful to construct a Born-Haber cycle.

lattice energy = $\mathrm{kJ} \mathrm{mol}^{-1}$

[ 5 ]

[Maximum number: 6]

Sodium oxide, $\mathrm{Na}_{2} \mathrm{O}$ , is a white crystalline solid with a high melting point.

(a)

Use the data below, and other suitable data from the Data Booklet, to calculate the lattice energy of sodium oxide, $\Delta H_{\text {latt }}^{\ominus} \mathrm{Na}_{2} \mathrm{O}(\mathrm{s})$ .

\begin{aligned} & \Delta H_{\text {latt }}^{\ominus} \mathrm{Na}_{2} \mathrm{O}(\mathrm{~s})= \\ & \mathrm{kJ} \mathrm{~mol}^{-1} \end{aligned}

[ 4 ]

(b)

State how $\Delta H_{\text {latt }}^{\ominus} \mathrm{Na}_{2} \mathrm{~S}(\mathrm{~s})$ differs from $\Delta H_{\text {latt }}^{\ominus} \mathrm{Na}_{2} \mathrm{O}(\mathrm{s})$ .

Indicate this by placing a tick $(\checkmark)$ in the appropriate box in the table.

Explain your answer.

[ 2 ]

(a)

The most common zinc mineral contains zinc(II) sulfide, ZnS .

[ 7 ]

(i)

Complete Fig. 1.2 to show the Born-Haber diagram for the ionic solid ZnS .

Include state symbols of relevant species.

Fig. 1.2

[ 3 ]

(ii)

Describe the trend in the first electron affinity of the Group 16 elements S to Te .

Explain your answer.

[ 2 ]

(iii)

Explain why the lattice energy, $\Delta H_{\text {latt }}$ , of ZnO is more exothermic than that of ZnS .

[ 2 ]

[Maximum number: 4]

Potassium chloride, KCl , and magnesium chloride, $\mathrm{MgCl}_{2}$ , are both ionic solids.

Table 1.1

(a)

Explain the reasons why the lattice energy of $\mathrm{MgCl}_{2}$ is more exothermic than the lattice energy of KCl.

[ 2 ]

(b)

Define the following terms.

[ 2 ]

(i)

enthalpy change of atomisation

[ 1 ]

(ii)

first electron affinity

[ 1 ]

(a)

(i)

Write an equation to represent the lattice energy of MgO .

[ 3 ]

(b)

Use the following data, together with appropriate data from the Data Booklet, to calculate a value of $\Delta H_{\mathrm{f}}^{\ominus}(\mathrm{MgO})$ .

\Delta H_{\mathrm{f}}^{\ominus}(\mathrm{MgO})=

[ 3 ]

(a)

(i)

The equation for the formation of a gaseous sulfate ion is shown.

\mathrm{S}(\mathrm{~s})+2 \mathrm{O}_{2}(\mathrm{~g})+2 \mathrm{e}^{-} \rightarrow \mathrm{SO}_{4}{ }^{2-}(\mathrm{g}) \quad \Delta H=\Delta H_{\mathrm{f}}^{\ominus} \text { of } \mathrm{SO}_{4}{ }^{2-}(\mathrm{g})

Calculate the standard enthalpy change of formation, $\Delta H_{\mathrm{f}}^{\ominus}$ , of $\mathrm{SO}_{4}{ }^{2-}(\mathrm{g})$ . It may be helpful to draw a labelled energy cycle. Use relevant data from Table 1.1 in your calculations.

Table 1.1

$\Delta H_{\mathrm{f}}^{\ominus}$ of $\mathrm{SO}_{4}{ }^{2-}(\mathrm{g})=$ $\mathrm{kJ} \mathrm{mol}^{-1}$

[ 3 ]

(ii)

Suggest how the lattice energy of $\mathrm{BaSO}_{4}(\mathrm{~s})$ differs from the lattice energy of $\mathrm{Cs}_{2} \mathrm{SO}_{4}(\mathrm{~s})$ . Explain your answer.

[ 2 ]

[Maximum number: 2]

Potassium iodide, KI, is used as a reagent in both inorganic and organic chemistry.

(a)

Table 1.1 gives some data about the halide ions, $\mathrm{Cl}^{-}, \mathrm{Br}^{-}$ and $\mathrm{I}^{-}$ , and their potassium salts.

Table 1.1

[ 2 ]

(i)

The ionic radius of $\mathrm{Pb}^{2+}$ is 0.120 nm compared to 0.133 nm for $\mathrm{K}^{+}$ .

Suggest how the $\Delta H_{\text {latt }}^{\ominus}$ of $\mathrm{PbI}_{2}(\mathrm{~s})$ differs from $\Delta H_{\text {latt }}^{\ominus}$ of KI(s).
Explain your answer.

[ 2 ]

Question 1

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