Describe the electrolysis of aqueous copper(II) sulfate with inert electrodes.

The solution contains $Cu^{2+}(aq)$, $SO_4^{2-}(aq)$, $H^+(aq)$, and $OH^-(aq)$ (from the dissociation of water). The electrodes are inert carbon.

At the cathode, reduction occurs. Possible species to be reduced are $Cu^{2+}$ and $H_2O$.
$Cu^{2+}(aq) + 2e^- \rightarrow Cu(s)$ ($E^\circ = +0.34 \text{ V}$)
$2H_2O(l) + 2e^- \rightarrow H_2(g) + 2OH^-(aq)$ ($E^\circ = -0.83 \text{ V}$ at pH 7)
Since $Cu^{2+}$ has a more positive standard reduction potential, copper metal will be deposited.
Observation 1: A reddish-brown solid is deposited on the cathode.

At the anode, oxidation occurs. Possible species to be oxidized are $SO_4^{2-}$ and $H_2O$ (or $OH^-$).
$2SO_4^{2-}(aq) \rightarrow S_2O_8^{2-}(aq) + 2e^-$ (requires very high potential)
$2H_2O(l) \rightarrow O_2(g) + 4H^+(aq) + 4e^-$ ($E^\circ = +1.23 \text{ V}$)
Water is more easily oxidized than sulphate ions.
Observation 2: Colorless gas bubbles are produced at the anode.

As $Cu^{2+}$ ions are removed from the solution, the characteristic blue color of copper(II) sulphate will fade.
Observation 3: The blue color of the solution fades.

Any two of these observations are acceptable.
The two observations are:

1. A reddish-brown solid is deposited on the cathode.
2. Colorless gas bubbles are produced at the anode.

At the cathode: $Cu^{2+}(aq) + 2e^- \rightarrow Cu(s)$
At the anode: $2H_2O(l) \rightarrow O_2(g) + 4H^+(aq) + 4e^-$

At the anode, water is oxidized, producing oxygen gas and hydrogen ions ($H^+$). The $H^+$ ions are released into the solution.

The accumulation of $H^+$ ions in the solution increases the concentration of hydrogen ions. An increase in $H^+$ concentration makes the solution more acidic. Therefore, the pH of the resultant solution will decrease.

Explanation: The pH of the resultant solution will decrease. This is because water is oxidized at the anode, producing hydrogen ions ($H^+$). The increase in $H^+$ concentration makes the solution more acidic, leading to a lower pH.