Question

A gas occupies a volume of 250 ml at 700 mm Hg pressure and 25 deg C. What additional pressure is required to reduce the gas volume to its 4/5 th value at the same temperature

Answer 1

$$\begin{gathered} Accordingtoidealgasequation \\ pV=nRT \\ 700\times 250=nR\times 298----1 \\ {P}_2\times 250\times \frac{4}{5}=nR\times 298----2 \\ Taketheratio \\ \frac{700\times 250=nR\times 298}{P_2\times 250\times \frac{4}{5}=nR\times 298} \\ {P}_2=700\times \frac{5}{4}=875mm \\ Sotheadditionalpressureneeded=875-700=175mmofHgpressure \end{gathered}$$