Explain the electrolysis of copper sulphate solution with platinum electrode
The electrolysis of copper sulphate solution with platinum electrodes involves the use of an electric current to separate the copper and sulphate ions in the solution. This process is carried out by setting up an electrolytic cell, which consists of two electrodes (one cathode and one anode) immersed in the copper sulphate solution.
To understand how the electrolysis of copper sulphate takes place, we must first understand the components of the solution:
1. Copper Sulphate (CuSO4): This is an ionic compound that dissociates in water to form copper ions (Cu2+) and sulphate ions (SO4^-2).
2. Platinum (Pt) Electrodes: Platinum is commonly used as an electrode material due to its stability and resistance to corrosion during electrolysis.
In the electrolytic cell, the platinum cathode (negative electrode) attracts the positively charged copper ions, while the platinum anode (positive electrode) attracts the negatively charged sulphate ions.
Here is a step-by-step explanation of the electrolysis process:
1. Setup: Fill a beaker or electrolytic cell with a copper sulphate solution. Place a platinum cathode and a platinum anode into the solution, making sure they do not touch each other.
2. Electric Current: Connect the cathode to the negative terminal of a power supply and the anode to the positive terminal. This completes the circuit, allowing the flow of electric current.
3. Cathode (Reduction): At the cathode, copper ions (Cu2+) in the solution gain electrons from the cathode and are reduced to form copper metal (Cu). The half-reaction can be represented as: Cu2+ + 2e^- -> Cu.
4. Anode (Oxidation): At the anode, sulphate ions (SO4^-2) in the solution lose electrons and are oxidized to form oxygen gas (O2) and water (H2O). The half-reaction can be represented as: 4OH^- -> O2 + 2H2O + 4e^-.
5. Overall Reaction: The reduction of copper ions at the cathode and oxidation of sulphate ions at the anode combine to form the overall reaction: Cu2+ + 4OH^- -> Cu + 2H2O + O2.
It is important to note that during the electrolysis process, the concentration of copper sulphate gradually decreases due to the deposition of copper on the cathode. This can be observed by the gradual change in the blue color of the solution to a pale blue or colorless appearance.
In summary, the electrolysis of copper sulphate solution with platinum electrodes involves the reduction of copper ions at the cathode, leading to the deposition of copper metal, and the oxidation of sulphate ions at the anode, resulting in the formation of oxygen gas and water.