Question

If isobutane and n-butane are present in a gas, then how much oxygen should be required for complete combustion of $5kg$ of this gas.

• A. $17.9kg$
• B. $9kg$
• C. $27kg$
• D. $1.8kg$

Answer 1

The correct option is A $17.9kg$

If isobutane and n-butane are present in a gas, then how much oxygen should be required for complete combustion of 10 kg of this gas:

Isobutane and n-Butane have same chemical formula $\left(C_4{H}_{10}\right)$ and give same combustion reaction.

$2C_4{H}_{10}+13O_2\to 8C{O}_2+10H_{2}O$

This means 2 moles of this mixture requires 13 moles of oxygen.

Molecular mass of butane=58g/mol

Molecular mass of oxygen=32g/mol

Thus, 116 g mixture needs $13\times 32g=416g$ oxygen

1 g mixture needs $=\frac{416}{116}g$ oxygen

5 kg of the mixture $=5\times {10}^{3}g$ needs $=\frac{416\times 5\times {10}^3}{116}=17900g$ of oxygen

Therefore, $17.9$ kg oxygen is used.