Question

Water gas is produced by

• A. Passing steam over red hot coke
• B. Passing steam and air over red hot
• C. Burnina coke is excess air
• D. Burning coke is limited supply of air

Answer 1

The Correct Option is A

To understand how water gas is produced, we need to look at the constituents and the chemical process involved.

Water gas is a synthesis gas, containing carbon monoxide (\text{CO}) and hydrogen gas (\text{H}_2). It is produced by the endothermic reaction between steam and carbon, typically in the form of coke. The reaction is as follows:

\text{C (s) + H}_2\text{O (g) → CO (g) + H}_2\text{(g)}

Let's evaluate the provided options:

• Passing steam over red hot coke: This is the correct method for producing water gas. The red-hot coke provides the necessary heat for the steam to react with carbon, producing carbon monoxide and hydrogen.
• Passing steam and air over red hot coke: While introducing air might facilitate combustion, it would not specifically lead to the production of water gas as intended in this reaction. Water gas production requires steam and coke in isolation for the specific reaction mentioned above.
• Burning coke in excess air: This would primarily lead to the production of carbon dioxide (\text{CO}_2) and does not produce the desired hydrogen component of water gas. The reaction for carbon burning in excess air is \text{C (s) + O}_2\text{ (g) → CO}_2\text{ (g)}.
• Burning coke in a limited supply of air: This results in the formation of carbon monoxide but without the hydrogen, as steam is not involved in this reaction. Therefore, it does not produce water gas but just forms carbon monoxide through partial combustion: \text{2C (s) + O}_2\text{ (g) → 2CO (g)}.

Thus, the correct answer is Passing steam over red hot coke, as this specific setup allows for the endothermic production of water gas, a mixture of carbon monoxide and hydrogen gas. This is a crucial industrial and chemical process used in syngas production.