Fill in the missing electronic configurations for a $\text{Cu}^+$ ion and a $\text{Cu}^{2+}$ ion. $\text{Cu}^+$ ion: $[\text{Ar}]$ ................................................................ $\text{Cu}^{2+}$ ion: $[\text{Ar}]$ ................................................................
Explain why transition elements show variable oxidation states.
A few drops of $\text{NH}_3(aq)$ are added to $\text{CuSO}_4(aq)$. Describe the observations made.
Write the equation for the reaction that occurs.
An excess of $\text{NH}_3(aq)$ is added to $\text{CuSO}_4(aq)$. Describe any further observations made.
Write the equation for the reaction that occurs.
State the name of the type of reaction occurring.
Acidified KMnO$_4$ can oxidise copper metal. The relevant half-equations, together with their standard electrode potentials, $E^\circ$, are shown. $\text{Cu}^{2+} + 2\text{e}^- \rightleftharpoons \text{Cu}$, $E^\circ = +0.34\text{ V}$ $\text{MnO}_4^- + 8\text{H}^+ + 5\text{e}^- \rightleftharpoons \text{Mn}^{2+} + 4\text{H}_2\text{O}$, $E^\circ = +1.52\text{ V}$ A MnO$_4^-$/\text{Mn}^{2+}$ electrode is set up using $0.0020\text{ mol dm}^{-3}$ MnO$_4^-$, $1.0\text{ mol dm}^{-3}$ Mn$^{2+}$ and $1.0\text{ mol dm}^{-3}$ H$^+$. The temperature used is $298\text{ K}$. Use the Nernst equation to show that the $E$ value for this MnO$_4^-$/\text{Mn}^{2+}$ electrode is $+1.49\text{ V}$.
An electrochemical cell is assembled using a standard Cu$^{2+}$/Cu electrode and the MnO$_4^-$/Mn$^{2+}$ electrode described in (d)(i). Calculate the value of $E_{\text{cell}}$.
Write the equation for the reaction that takes place in the electrochemical cell described in (d)(ii).
Complete the sentences for the electrochemical cell described in (d)(ii). The ......................... electrode is the negative electrode. Electrons flow from the ......................... electrode to the ......................... electrode when the cell is in use.
A solution containing $[\text{Cu(H}_2\text{O)}_6]^{2+}$ is electrolysed for $5.00$ hours using a constant electric current. $0.764\text{ g}$ of copper metal is formed at the cathode. No other reduction reaction takes place. Calculate the electric current, in A, used. Give your answer to three significant figures.