How is Copper Sulphate Made?

You may not have access to a chemistry lab, but you can still make copper sulphate crystals at home.
The two main ingredients are copper and sulphuric acid, but simply adding copper to a diluted acidic solution will not promote the oxidation reaction. This is because the standard reduction potential of copper (+0.52) is higher that hydrogen (0.00), which means copper has a lower tendency to lose electrons than hydrogen. In practical terms, this means copper cannot reduce hydrogen (from H2SO4), and therefore the reaction does not occur. To “help” the reaction, either a concentrated solution of H2SO4 (added to copper oxide) or electricity are required.

Make copper sulphate at home

Here we’ll explain a method using copper wire and battery fluid (sulphuric acid). The method needs electricity to promote the reaction between the reagents. Materials needed include copper wire (as a source of copper) and battery fluid (diluted sulphuric acid, H2SO4); as well as a 6-volt battery.
In a container with diluted sulphuric acid (add some water if necessary) place two copper wires connected to a 6-volt battery. It’s important to make sure the copper wires do not touch each other. The solution very quickly turns blue, as the reaction occurs to produce copper sulphate.
Cu + 2 H2SO4 = CuSO4 + SO2 + 2 H2O
When electricity runs through the copper wires, bubbles of gas will start from the negative electrode, while copper will start dissolving from the positive electrode, oxidised by the electrical current. As Cu2+ reacts with SO42-, copper sulphate (CuSO4) is produced. To recover this compound as powder, the best way is to boil the solution. At this stage, it’s essential to be very careful, because as the water evaporates, the acidic solution becomes increasingly concentrated. It’s advisable to conduct this experiment in a well-ventilated area wearing appropriate protective equipment, such as gloves and mask.
As you boil the water, copper sulphate will begin to precipitate at the bottom of the container. At this stage, it’s possible to recover the sulphuric acid solution to be used again. However, if you prefer to have copper sulphate crystals, grow them straight from the blue solution simply by letting it evaporate.

Industrial processes

In industrial settings, copper sulphate is extracted from copper ores or from nonferrous scrap. After extraction, copper is dissolved in diluted sulphuric acid in the presence of air, producing a saturated liquor. To obtain copper sulphate crystals, this solution is allowed to cool down slowly in large containers with lead strips to provide a surface for crystals to grow on. If only the powder is required, the cooling process can be accelerated.