An aqueous solution of sodium hydroxide is electrolysed using inert electrodes. Oxygen gas is produced at the positive electrode (anode), and hydrogen gas is produced at the negative electrode (cathode).
Complete the half-equation for the production of oxygen gas at the positive electrode: 4OH−→O2+2H2O+‾e−4\text{OH}^- \rightarrow \text{O}_2 + 2\text{H}_2\text{O} + \underline{\quad} \text{e}^-4OH−→O2+2H2O+e−
The overall chemical equation for this electrolysis reaction is: 2H2O(l)→2H2(g)+O2(g)2\text{H}_2\text{O}(\text{l}) \rightarrow 2\text{H}_2(\text{g}) + \text{O}_2(\text{g})2H2O(l)→2H2(g)+O2(g)
If 42 cm342\text{ cm}^342 cm3 of hydrogen gas is collected, what volume of oxygen gas is collected under the same conditions of temperature and pressure?