Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

This question deals with electrode potentials and thermochemistry.
(a)[2]

Define standard electrode potential, $E^\circ$, and include what is meant by standard conditions.

(b(i))[3]

An electrochemical cell is assembled to determine $E^\circ$ for the $\text{Ag}^+(aq)/\text{Ag}(s)$ electrode. Draw a labelled diagram of this electrochemical cell. Include every substance needed. It is not necessary to state the conditions used.

(b(ii))[1]

A separate electrochemical cell is set up using a lower concentration of $\text{Ag}^+(aq)$ than that used in (b)(i). Suggest how the electrode potential, $E$, for the $\text{Ag}^+(aq)/\text{Ag}(s)$ electrode would change from its $E^\circ$ value. Explain your answer.

(c)[1]

Define enthalpy change of solution, $\Delta H^\circ_{\text{sol}}$.

(d(i))[2]

Table 4.1 gives some relevant energy changes for $\text{AgNO}_3$. Complete the energy cycle in Fig. 4.1 so that it shows how the lattice energy, $\Delta H^\circ_{\text{latt}}$, of $\text{AgNO}_3\text{(s)}$ is related to the energy changes listed in Table 4.1. Add state symbols for all species.

(d(ii))[1]

Calculate the lattice energy, $\Delta H^\circ_{\text{latt}}$, of $\text{AgNO}_3\text{(s)}$.

(e)[3]

Suggest the pattern in the magnitude of the lattice energies of the metal nitrates, $\text{NaNO}_3(s)$, $\text{Mg(NO}_3)_2(s)$ and $\text{RbNO}_3(s)$. Explain your answer.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: Half-cell voltage measured against SHE

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