Chemistry 9701 · AS & A Level · Chemical energetics

Chemical energetics — practice question

(a)[1]

Put one tick ($\checkmark$) in every row of Table 3.1 to show the sign of each type of energy change under standard conditions.

(b)[2]

Define the standard enthalpy change of atomisation.

(c)[3]

Calculate the lattice energy, $\Delta H^\circ_{\text{latt}}$, of $\text{Ag}_2\text{O(s)}$ using the relevant data from Table 3.2. Drawing a labelled energy cycle may help. Show your working.

(d)[2]

Suggest the pattern in the magnitudes of the lattice energies of the silver compounds $\text{Ag}_2\text{S}$, $\text{Ag}_2\text{O}$ and $\text{Ag}_2\text{Se}$. Explain your answer.

(e(i))[1]

Give the expression for the solubility product, $K_{\text{sp}}$, of $\text{Ag}_2\text{SO}_3$.

(e(ii))[1]

Calculate the equilibrium concentration of $\text{Ag}^+$ in a saturated solution of $\text{Ag}_2\text{SO}_3$ at $298\,\text{K}$. $[K_{\text{sp}}\ \text{Ag}_2\text{SO}_3 = 1.50 \times 10^{-14}\,\text{mol}^3\,\text{dm}^{-9}]$

(f)[2]

The standard enthalpy change of solution, $\Delta H^{\circ}_{\text{sol}}$, of $\text{AgNO}_3\text{(s)}$ in water is $+22.6\,\text{kJ mol}^{-1}$. Suggest how the feasibility of dissolving $\text{AgNO}_3\text{(s)}$ in water changes as temperature increases. Explain your answer.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: Bond energy and atomisation are always positive, whereas enthalpy of formation can be positive or negative.

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