Complete the electronic configurations for a $\text{Cu}^+$ ion and a $\text{Cu}^{2+}$ ion. $\text{Cu}^+$ ion: $[\text{Ar}]\,\ldots$ ; $\text{Cu}^{2+}$ ion: $[\text{Ar}]\,\ldots$
Explain why transition elements have variable oxidation states.
A few drops of $\text{NH}_3(aq)$ are added to $\text{CuSO}_4(aq)$. Describe any observations made.
Write an 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 an equation for the reaction that occurs.
State the name for the type of reaction taking place.
Copper metal can be oxidised by acidified $\text{KMnO}_4$. The relevant half-equations and their standard electrode potentials, $E^\circ$, are shown. $\text{Cu}^{2+} + 2e^- \rightleftharpoons \text{Cu}$, $E^\circ = +0.34\,\text{V}$ $\text{MnO}_4^- + 8\text{H}^+ + 5e^- \rightleftharpoons \text{Mn}^{2+} + 4\text{H}_2\text{O}$, $E^\circ = +1.52\,\text{V}$ A $\text{MnO}_4^- / \text{Mn}^{2+}$ electrode is made using $0.0020\,\text{mol dm}^{-3}$ $\text{MnO}_4^-$, $1.0\,\text{mol dm}^{-3}$ $\text{Mn}^{2+}$ and $1.0\,\text{mol dm}^{-3}$ $\text{H}^+$. The temperature is $298\,\text{K}$. Use the Nernst equation to show that the $E$ value for this $\text{MnO}_4^- / \text{Mn}^{2+}$ electrode is $+1.49\,\text{V}$.
An electrochemical cell is set up with a standard $\text{Cu}^{2+}/\text{Cu}$ electrode and the $\text{MnO}_4^- / \text{Mn}^{2+}$ electrode described in (d)(i). Calculate $E_{\text{cell}}$. $E_{\text{cell}} =$ …………………… $\text{V}$
Write an equation for the reaction that occurs 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 with a constant electric current. $0.764\,\text{g}$ of copper metal is formed at the cathode. No other reduction reaction occurs. Calculate the current, in A, used. Give your answer to three significant figures. current = …………………… $\text{A}$