The relation between pressure exerted by an ideal gas `(p_("ideal"))` and observed pressure `(p_("real"))` is given by the equation
`P_("ideal")=P_("real")+(an^(2))/(V^(2))`
(i) If pressure is taken in `Nm^(-2)`, number of moles in mol and volume in `m^(3)`, Calculate the unit of .a..
(ii) What will be the unit of .a. when pressure is in atmosphere and volume in `dm^(3)` ?

Explanation

Given that, `P_("ideal")=P_("real")+(an^(2))/(V^(2))`
(i) a = If units of `p = Nm^(2)`,
units of `V=m^(3)`, units of n = mol
then, units of `a =(Nm^(-2)(m^(3))^(2))/((mol)^(2))=Nm^(4)mol^(-2)`
(ii) If units of p = atm, units of `V = dm^(3)`, units of n = mol
then, units of `a = (pV^(2))/(n^(2))=(atm.(dm^(3))^(2))/((mol)^(2))`
= atm `dm^(6)mol^(-2)`