Question

On electrolysis of dil.sulphuric acid using Platinum (Pt) electrode, the product obtained at anode will be:

• A. Hydrogen gas
• B. Oxygen gas
• C. $H_2S$ gas
• D. $SO_2$ gas

Answer 1

The Correct Option is B

To determine the product obtained at the anode during the electrolysis of dilute sulfuric acid using a platinum (Pt) electrode, we need to understand the fundamental processes occurring during electrolysis.

Electrolysis involves the decomposition of a substance by passing an electric current through it. In the case of dilute sulfuric acid (\(H_2SO_4\)), the electrolysis occurs as follows:

• The water (\(H_2O\)) in the sulfuric acid solution undergoes electrolysis.
• At the cathode (negative electrode), protons (\(H^+\) ions) are reduced to produce hydrogen gas:

\(2H^+ + 2e^- \rightarrow H_2 \uparrow\)

• At the anode (positive electrode), water is oxidized to produce oxygen gas:

\(2H_2O \rightarrow O_2 \uparrow + 4H^+ + 4e^−\)

Thus, during the electrolysis of dilute sulfuric acid with a platinum anode, the gas evolved at the anode is oxygen gas. This is because water molecules undergo oxidation, releasing oxygen gas as a result.

Let's evaluate the options:

• Hydrogen gas: This is incorrect because hydrogen gas is produced at the cathode, not the anode.
• Oxygen gas: Correct, as explained above, oxygen gas is evolved at the anode.
• \(H_2S\) gas: Incorrect, as hydrogen sulfide is not a product of this electrolysis process.
• \(SO_2\) gas: Incorrect, sulfur dioxide gas is not produced during the electrolysis of dilute sulfuric acid.

Therefore, the correct answer is that oxygen gas is obtained at the anode when dilute sulfuric acid is electrolyzed using a platinum electrode.