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=(pV^(2))/n^(2)` 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)`