What is Water Gas?

Water gas is a fuel gas mixture primarily composed of carbon monoxide (CO) and hydrogen (H₂). It is produced by passing steam over red-hot coke (carbon) at a high temperature. The chemical reaction involved is:

$C+H_{2}O\stackrel{1000°C}{\to }\mathrm{CO}+H_2$

This process is known as the water-gas reaction. Water gas is used as a fuel and as a source of hydrogen in various industrial processes.

Step-by-Step Analysis of the Options:

Step 1: Review the definition of water gas. It is specifically defined as a mixture of CO and H₂.

Step 2: Evaluate each option:

• CO + N₂: This is not water gas; it is producer gas.
• CO + CO₂: This is not a standard named gas mixture.
• CO + N₂ + H₂: This is not water gas; it is a modified form of producer gas.
• CO + H₂: This matches the exact composition of water gas.

Final Answer: The correct option is CO + H₂.

Related Topics & Formulae

Producer Gas: Another important fuel gas, produced by blowing air through red-hot coke. Its main components are carbon monoxide (CO) and nitrogen (N₂). The reaction is:
$2C+O_2+4N_2\to 2\mathrm{CO}+4N_2$

Water-Gas Shift Reaction: A related industrial process used to increase the hydrogen content of water gas. Carbon monoxide reacts with steam to form carbon dioxide and more hydrogen.
$\mathrm{CO}+H_{2}O\rightleftharpoons C{O}_2+H_2$

Key Theory: The production of these gases is a classic example of applying thermochemistry. The water-gas reaction is endothermic (absorbs heat), while the producer gas reaction is exothermic (releases heat). This is why they are often produced together in a cyclic process to maintain the temperature of the coke bed.