Complete the balanced equation for the overall reaction in a hydrogen fuel cell. [2 marks] H2 +  H2O

To complete the balanced equation for the overall reaction in a hydrogen fuel cell, we need to identify the reactants and products involved.

1. Break Down the Problem

The equation provided is:
$\text{H}_2 + \rightarrow \text{H}_2\text{O}$ We recognize that hydrogen gas (H₂) is reacting to produce water (H₂O). The missing reactant is oxygen gas (O₂).

2. Relevant Concepts

The balanced reaction will involve the reaction of diatomic hydrogen (H₂) with diatomic oxygen (O₂) to produce water (H₂O). The stoichiometry of the reaction must also be balanced.

3. Analysis and Detail

The balanced half-reaction for hydrogen oxidation is: $\text{2 H}_2 + \text{O}_2 \rightarrow \text{2 H}_2\text{O}$ This shows that 2 molecules of hydrogen gas react with 1 molecule of oxygen gas to produce 2 molecules of water.

4. Verify and Summarize

To verify the balance, we check the number of atoms:

• Reactants: 4 Hydrogen (2 H₂) and 2 Oxygen (1 O₂)
• Products: 4 Hydrogen (2 from 2 H₂O) and 2 Oxygen (1 from 2 H₂O)

Both sides have equal numbers of each type of atom, confirming that the equation is balanced.

Final Answer

The complete balanced equation for the overall reaction in a hydrogen fuel cell is: $\text{2 H}_2 + \text{O}_2 \rightarrow \text{2 H}_2\text{O}$