Question

A sample of gas in a balloon has an initial temperature of 27 ∘C and a volume of 1290 L . If the temperature changes to 63 ∘C , and there is no change of pressure or amount of gas, what is the new volume, V2, of the gas?

Answer 1

Ans. Charles’ Law: Volume (V) of a gas in a closed vessel is directly proportional to absolute temperature (T).

That is,            V₁ / T₁ = V₂ / T₂                   - Pressure constant

Note: the temperature must be in terms of “absolute temperature, K”

            Or, 1290 L / 300.15 K = V2 / 336.15 K

            Or, V2 = (1290 L / 300.15 K) x 336.15 K

            Hence, V2 = 1444.72 L

Therefore, Volume of gas at 63.0⁰C = 1444.72 L

Note: There is no need of calculating the moles of gas at 27.0⁰C using ideal gas equation and then fitting the value of “n” at 63.0⁰C to get new value. Charles’s law jus does the same thing.