A gas at 240 K is heated to 127°C. Find the percentage change in the volume of the gas (pressure remaining constant).

V₁ = Initial volume of the gas = V cc
T₁ = Initial temperature of the gas = 240 K
T₂ = Final temperature of the gas = 127°C = 127 + 273 = 400 K
V₂ = Final volume of the gas = ?

By Charles' Law:

$\dfrac{\text{V}$1}{\text{T}1} = \dfrac{\text{V}2}{\text{T}2}

Substituting the values :

$\dfrac{\text{V}}{240} = \dfrac{\text{V}$2}{400} \\[1em] \text{V}2 = \dfrac{400 \times \text{V}}{240} \\[1em] \text{V}_2 = \dfrac{5\times \text{V}}{3}

Increase in vol. = $\dfrac{5\text{V}}{3}$ - V = $\dfrac{2\text{V}}{3}$

Percentage increase in vol. = $\dfrac{\text{Increase}}{\text{Original}}$ x 100 = $\dfrac{2\text{V}}{3\text{V}}$ x 100 = 66.67%

∴ Percentage increase in the volume of the gas = 66.67%