Question

If 10 volumes of dihydrogen gas reacts with five volumes of dioxygen gas, how many volumes of water vapour would be produced?

Answer 1

Step 1: Write the Balanced Equation

Reaction of dihydrogen with dioxygen: 2H2(g) + O2(g) -> 2H2O(g)

Step 2: Use Volumetric Stoichiometry

For gases at the same temperature and pressure, volume ratio = mole ratio (Avogadro’s law).

From the balanced equation: \[ 2 \ \text{vol H}_2 : 1 \ \text{vol O}_2 : 2 \ \text{vol H}_2\text{O} \]

Step 3: Apply to Given Volumes

Given: \[ 10 \ \text{vol H}_2,\quad 5 \ \text{vol O}_2 \]

• Required O₂ for 10 vol H₂: \[ \frac{10}{2} = 5 \ \text{vol O}_2 \] which is exactly available, so both reactants are in stoichiometric proportion.
• According to the ratio, 2 vol H₂ → 2 vol H₂O, so 10 vol H₂ → 10 vol H₂O.

Final Answer

The volume of water vapour produced is \[ \boxed{10 \ \text{volumes of H}_2\text{O vapour}}. \]