Question

280 g of a mixture of ch4 and c2h6 in 5:2 molar ratio is burnt in presence of excess of oxygen. Calculate total moles of CO2

Answer 1

From the given ratio we can get the masses of the two compounds.

From the ratio the mass of CH₄ will be :

5/7 × 280 = 200 g

The mass of C₂H₆ will be :

2/7 × 280 = 80 g

Equation for combustion of both is :

CH₄ + 2O₂ —> CO₂ + 2 H₂O

The moles of CH₄ are :

200 / 16 = 12.5 moles.

The mole ratio of CH₄ to CO₂ is 1 : 1 and hence moles of CO₂ are 12.5 moles.

C₂H₆ + 3.5O₂ —> 2CO₂ (g) + 3H₂O

Moles of C₂H₆ are :

80/30 = 2.667 moles.

The mole ratio is 1 : 2

Moles of CO₂ will be :

2 × 2.667 = 5.334 moles.

Total moles :

5.334 + 12.5 = 17.834 moles