Final answer:
To separate chrome and nickel from a mixed solution containing their salts, selective precipitation, pH manipulation, temperature control, and complexation can be used to exploit differences in solubility and chemical properties.
Step-by-step explanation:
To separate chrome and nickel from a solution containing nickel sulphate, nickel chloride, and chrome salt, we need to precipitate one of the metals while keeping the other in solution. This can be achieved by making use of their different solubility properties and by manipulating conditions such as precipitation, pH, temperature, and formation of complex ions.
One approach is to exploit the differences in solubility between chromium and nickel compounds. For instance, adding a base like sodium carbonate may precipitate one of the metals as its corresponding hydroxide. The precipitated hydroxide can then be filtered off. If both metals precipitate, it might be possible to redisolve one by altering the pH or temperature of the solution. Alternatively, adding a ligand such as ammonia can form a soluble complex with one of the metals, leaving the other to precipitate.
If the goal is to separate specifically chrome as chromium salts, a selective precipitation reaction can be performed. By manipulating the redox potential or by the addition of specific compounds, we can cause the selective precipitation of chromium compounds, like chromates.