Question

Mass of methane required to produce 22 g of CO₂​ after complete combustion is ______ g.
(Given Molar mass in g mol⁻¹: C=12.0, H=1.0, O=16.0).

Answer 1

Correct Answer: 8

The combustion of methane (CH₄) can be represented by the balanced chemical equation:
CH₄ + 2O₂ → CO₂ + 2H₂O.
To find the mass of methane required to produce 22 g of CO₂, we proceed as follows:
Step 1: Determine the molar mass of CO₂
Molar mass of CO₂ = C + 2(O) = 12.0 + 2(16.0) = 44.0 g/mol.
Step 2: Calculate the moles of CO₂ produced
Moles of CO₂ = mass/molar mass = 22 g / 44.0 g/mol = 0.5 mol.
Step 3: Use the stoichiometry of the reaction to find moles of CH₄
According to the balanced equation, 1 mole of CH₄ produces 1 mole of CO₂. Therefore, 0.5 mol of CO₂ requires 0.5 mol of CH₄.
Step 4: Determine the mass of CH₄
Molar mass of CH₄ = C + 4(H) = 12.0 + 4(1.0) = 16.0 g/mol.
Mass of CH₄ = moles × molar mass = 0.5 mol × 16.0 g/mol = 8 g.
The mass of methane required is 8 g, 

Answer 2

CH₄ + 2O₂ → CO₂ + 2H₂O

Moles of CO₂ produced:

\[ \frac{22}{44} = 0.5 \, \text{mol} \]

Required moles of CH₄:

\[ 0.5 \, \text{mol} \times 16 \, \text{g/mol} = 8 \, \text{g} \]