Copper sulphate is a useful chemical used to electroplate copper onto various metallic items; it’s also used to control algae growth and to make blue crystals. It can easily be purchased cheaply online but if you’re a nerd like me you’ll have more fun making it yourself.
This method will show you how to make it using battery acid (sulphuric acid) and some copper wires.
Insert the ends of copper wires connected to a battery into a jar of sulphuric acid without the touching. The anode(+) could be connected to a large copper sheet or piece of copper pipe to increase surface area. Copper ions will be deducted from the anode and replaced with the hydrogen ions in the acid. The hydrogen ions will combine and be released as hydrogen gas. Your anode will eventually disintegrate and will need to be replaced.
H2SO4 + Cu => H2 + CuSO4
When no more hydrogen gas is produced the reaction is complete and you have copper sulphate dissolved in water. This can be evaporated into crystals.