Use the graph to work out the rate of reaction at $40\,\text{s}$. Show all your working.
Use the graph to demonstrate that the overall reaction is first order. Explain your answer.
In another reaction that is also first order, $75\%$ of the reactant is consumed in $320\,\text{s}$. Calculate the rate constant, $k$, for this reaction. State the units for $k$.
Define the term standard electrode potential, $E^\circ$.
A salt bridge is included in an electrochemical cell. State the role of the salt bridge. Explain your answer.
Complete the diagram of the apparatus that can be used to measure the $E^\circ$ of the $\text{Cr}_2\text{O}_7^{2-}(aq),\ \text{H}^+(aq)/\text{Cr}^{3+}(aq)$ electrode against the standard hydrogen electrode. Your diagram should be fully labelled so that all apparatus, substances and conditions are identified.
The $E^\circ$ of the $\text{Cr}_2\text{O}_7^{2-}(aq),\ \text{H}^+(aq)/\text{Cr}^{3+}(aq)$ electrode is $+1.33\,\text{V}$. Label the negative electrode and show the direction of electron flow in the external circuit for the current flow shown in your diagram in (c)(iii).
Ethanal is oxidised to ethanoic acid in the presence of $\text{Cr}_2\text{O}_7^{2-}$ ions. Write the ionic equation for the oxidation of ethanal to ethanoic acid using dichromate(VI) in acid conditions. Calculate the $E^\circ_{\text{cell}}$ for this reaction.
In an ethanol-oxygen fuel cell, $\text{CH}_3\text{CH}_2\text{OH}(l)$ and $\text{O}_2(g)$ are each in contact with two inert electrodes immersed in an acidic solution. The cell reaction for the oxidation of ethanol by oxygen is shown. $2\text{CH}_3\text{CH}_2\text{OH} + \text{O}_2 \rightarrow 2\text{CH}_3\text{COOH} + 2\text{H}_2\text{O}$ $E^\circ_{\text{cell}} = +2.01\,\text{V}$ Calculate $\Delta G^\circ$, in $\text{kJ mol}^{-1}$, for the oxidation of ethanol by oxygen.