Question

Which of the following represents the water-gas shift reaction?

• A. \(C(s)+H_{2}O(g)\xrightarrow{1270K}CO(g)+H_{2}(g)\)
• B. \(CH_{4}(g)+H_{2}O(g)\xrightarrow[Ni]{1270K}CO(g)+3H_{2}(g)\)
• C. \(CO(g)+H_{2}O(g)\xrightarrow[catalyst]{673K}CO_{2}(g)+H_{2}(g)\)
• D. \(CH_{4}(g)+2O_{2}(g)\rightarrow CO_{2}(g)+2H_{2}O(l)\)

Hint:

Remember: Water gas formation = \(C+H_2O\), Water gas shift = \(CO+H_2O\).

Answer 1

The Correct Option is C

Step 1: Recall the water-gas shift reaction.
In this industrial step carbon monoxide reacts with steam to give more hydrogen, \[ \text{CO}(g) + \text{H}_2\text{O}(g) \rightleftharpoons \text{CO}_2(g) + \text{H}_2(g) \]
Step 2: Test option A.
$C + \text{H}_2\text{O} \rightarrow \text{CO} + \text{H}_2$ is the formation of water gas, not the shift reaction, so reject it.
Step 3: Test option B.
$\text{CH}_4 + \text{H}_2\text{O} \rightarrow \text{CO} + 3\text{H}_2$ is steam reforming of methane, also not the shift, so reject it.
Step 4: Test option C.
$\text{CO} + \text{H}_2\text{O} \rightarrow \text{CO}_2 + \text{H}_2$ exactly matches the shift reaction, where CO is oxidized to $\text{CO}_2$.
Step 5: Test option D.
$\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}$ is simple combustion, so reject it.
Step 6: Conclude.
Only option C is the water-gas shift reaction, option 3.
\[ \boxed{\text{CO} + \text{H}_2\text{O} \rightarrow \text{CO}_2 + \text{H}_2} \]