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))`
If pressure is taken in N `m^(-2)`, number of moles in mol and volume in `m^(3)`, calculate the unit of 'a'. What will be the unit of 'a' when pressure is in atmosphere is in atmosphere and volume in `dm^(3)` ?

Explanation

`p_("ideal")=p_("real")+(an^(2))/(V^(2))`
If pressure is in `"N m"^(-2)`
`(an^(2))/(V^(2))=p_("ideal")-p_("real")`
`("a mol"^(2))/(m^(6))=Nm^(-2)-Nm^(-2)=Nm^(-2)`
`"or "a=("N m"^(-2)xxm^(6))/("mol"^(2))="N m"^(4)"mol"^(-2)`
If pressure is in atm
`("a mol"^(2))/(dm^(6))=" atm or a "="atm dm"^(6)"mol"^(-2)`