Question

consider the following reaction. co₂(g) + h₂(g) ——→ co(g) + h₂o(l) what is being oxidized? ○ carbon ○ carbon dioxide ○ oxygen ○ hydrogen

Explanation:

1. First, recall the definitions: Oxidation is the loss of electrons (increase in oxidation state), reduction is the gain of electrons (decrease in oxidation state).
2. Determine the oxidation states:

• In \( \ce{H2(g)} \), the oxidation state of \( \ce{H} \) is \( 0 \) (since it is in its elemental form).
• In \( \ce{H2O(l)} \), the oxidation state of \( \ce{H} \) is \( + 1 \) (oxygen has an oxidation state of \( - 2 \), and for the compound to be neutral, \( 2\times(+1)+(-2)=0 \)).
• For \( \ce{C} \) in \( \ce{CO2} \): Let the oxidation state of \( \ce{C} \) be \( x \). Oxygen has an oxidation state of \( - 2 \), so \( x + 2\times(-2)=0\Rightarrow x = + 4 \). In \( \ce{CO} \), let the oxidation state of \( \ce{C} \) be \( y \), then \( y+(-2)=0\Rightarrow y = + 2 \). So carbon is reduced (oxidation state decreases from \( + 4 \) to \( + 2 \)).
• Oxygen in \( \ce{CO2} \), \( \ce{CO} \) and \( \ce{H2O} \) has an oxidation state of \( - 2 \), so it does not change.

1. Analyze hydrogen: The oxidation state of \( \ce{H} \) in \( \ce{H2} \) is \( 0 \), and in \( \ce{H2O} \) it is \( + 1 \). Since the oxidation state of hydrogen increases (from \( 0 \) to \( + 1 \)), hydrogen is oxidized.

Answer:

D. hydrogen