Question

What does A and B represent in Van der Waals?

Answer 1

Van der Waals equation

1. Van der Waal equation is the modified form of the Ideal gas equation which is applicable for real gases.
2. It states the relationship between the temperature, Pressure, Volume, and amount of real gases.
3. It can be written as $$\begin{gathered} \left(\mathrm{P}+\frac{{\mathrm{an}}^2}{{\mathrm{V}}^2}\right)\left(V-nb\right)=\mathrm{nRT} \\ \mathrm{where}\mathrm{P}=\mathrm{pressure} \\ \mathrm{V}=\mathrm{volume} \\ \mathrm{T}=\mathrm{temperature} \\ \mathrm{R}=\mathrm{Gas}\mathrm{constant} \\ \mathrm{n}=\mathrm{number}\mathrm{of}\mathrm{moles} \\ \mathrm{a}\mathrm{and}\mathrm{b}\mathrm{are}\mathrm{Van}\mathrm{der}\mathrm{Waals}\mathrm{constant}. \end{gathered}$$

a and b in the Van der Waal equation

1. a signifies the intermolecular forces of attraction between the molecules.
2. The S.I unit of a is${\mathrm{L}}^2\mathrm{atm}{\mathrm{mol}}^{-2}$.
3. b signifies the volume of gas per mole occupied.
4. The S.I unit of b is${\mathrm{Lmol}}^{-1}$.
5. The value of b is much smaller than the value of a.
6. The value of a and b increases with an increase in the size of the molecule.