A teacher sets up an experiment to investigate the electrolysis of aqueous sodium chloride, NaCl\text{NaCl}NaCl. The teacher measures the volume of hydrogen gas given off at regular intervals.
The plotted results are shown on the graph below:
Which electrode (negative or positive) is hydrogen gas given off at?
State the name of the product made at the other electrode.
Using the trend shown in the graph, what is the volume of hydrogen gas given off after 222222 minutes?
A student repeats the teacher's experiment with aqueous copper(II) sulfate, CuSO4\text{CuSO}_4CuSO4. The student finds that no hydrogen gas is given off.
Explain why hydrogen gas is given off in the electrolysis of aqueous NaCl\text{NaCl}NaCl, but not in the electrolysis of aqueous CuSO4\text{CuSO}_4CuSO4.
In the electrolysis of aqueous copper(II) sulfate, copper metal is also made.
Explain how the student could adapt the experiment to measure the mass of copper metal formed.