Edexcel A-Level Chemistry A2 16.4 The Features of the Standard Hydrogen Electrode and Understand Why a Reference Electrode Is Necessary Questions

Practise Edexcel IAL Chemistry 16.4 by labelling the standard hydrogen electrode, connecting it to a reference half-cell and explaining the role of platinum black.

Exam points

Label Pt or platinum black, H2 at 100 kPa, 1 mol dm^-3 H+ and 298 K in diagrams.
Connect the SHE to another half-cell with a salt bridge and high-resistance voltmeter.
Explain why platinum black increases the rate of the H2 and H+ equilibrium.

[Maximum number: 3]

This question is about mercury, Hg, and its compounds.
Mercury is a liquid element in the same group of the Periodic Table as zinc.
The electronic configuration of mercury is $[\mathrm{Xe}] 4 \mathrm{f}^{14} 5 \mathrm{~d}^{10} 6 \mathrm{~s}^{2}$ .

Mercury(I) chloride, $\mathrm{Hg}_{2} \mathrm{Cl}_{2}$ , is also known as calomel.

A saturated calomel electrode may be used as an alternative to the standard hydrogen electrode.

Figure for Question Edexcel A-Level Chemistry A2 16.4 The Features of the Standard Hydrogen Electrode and Understand Why a Reference Electrode Is Necessary Questions question 1 — Edexcel A-Level Chemistry A2

The half-equation for the calomel electrode is

\mathrm{Hg}_{2} \mathrm{Cl}_{2}(\mathrm{~s})+2 \mathrm{e}^{-} \rightleftharpoons 2 \mathrm{Hg}(\mathrm{l})+2 \mathrm{Cl}^{-}(\mathrm{aq})

The standard electrode potential of the calomel electrode is $E^{\ominus}=+0.24 \mathrm{~V}$ .

Add labels to complete the diagram of a standard hydrogen electrode. Include details of any essential conditions.
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Edexcel A-Level Chemistry A2 16.4 The Features of the Standard Hydrogen Electrode and Understand Why a Reference Electrode Is Necessary Questions question 1