Question

112 cm^3 of nitrogen gas is collected at a pressure of 720 mm of mercury.If the temperature remains constant,find its volume when the pressure is:

1. 760 mm cm^3 of mercury
2. 20 cm of mercury
3. Pressure drops by 40% of initial Pressue

Answer 1

As the temperature is constant so, let us use Boyle's law to find the new volume.
Initial pressure, P₁ = 720 mm og Hg = 72 cm of Hg
Initial Volume, V₁ = 112 cm³
Applying Boyle's law,
$$\begin{gathered} 1.P_1{V}_1=P_2{V}_2 \\ \Rightarrow 72\times 112=76\times V_2 \\ \Rightarrow V_2=\frac{72\times 112}{76}=106.10{\mathrm{cm}}^3 \\ 2.P_1{V}_1=P_3{V}_3 \\ \Rightarrow 72\times 112=20\times V_3 \\ \Rightarrow V_3=\frac{72\times 112}{20}=403.2{\mathrm{cm}}^3 \\ 3.P_1{V}_1=P_4{V}_4 \\ \Rightarrow 72\times 112=20\times V_4 \\ \Rightarrow V_4=\frac{72\times 112}{0.6\times 72}=186.67{\mathrm{cm}}^3 \end{gathered}$$