Chemistry - Real Gas Question with Solution | TestHub

(A) $-p,s(\mathrm{B})-r$ (C) $-p,q$ (D) $-r$ Explanation van der Waals' equation $$\left(p+\frac{n^{2}a}{V_m^2}\right)\left(V_m-b\right)=nRT$$ For hydrogen gas $(p=200\mathrm{atm},T=273\mathrm{K})$ As pressure is large $V_m$ can be assumed small, thus ' $b$ ' can not be ignored, while due to high pressure $a/V_m^2$ can be considered negligible in comparison to $p$. $$p\left(V_m-b\right)=RT\text{ and }Z=1+\frac{pb}{RT}$$ For hydrogen gas $(p\sim 0,T=273\mathrm{K})$ when pressure occurs of low about $1\mathrm{atm}$ or less and temperature is not very close to the point of liquification $\left[T_c\left({\mathrm{H}}_2\right)=33.3\mathrm{K}\right]$ gas behaves ideally. For $$PV=nRT$$ Temperature is close to the point of liquification $\left[T_C\left({\mathrm{CO}}_2\right)=304.2\right]$ thus, deviation from ideality appears very high (due to high attractive force of attraction). For real gas with very large molar volume. As molar volume is very large $a/V_m^2$ will be negligible and at the same time ' $b$ ' in comparison to $V_m$ is also considered negligible, thus, $p{V}_m=nRT$