Compressibility factor of 2 mol of `NH_(3)` gas at `27^(@)C` and 9.18 atm pressure is 0.931. if the volume of the gas molecules is not taken into consideration, then what is the value of van der waals constant 'a' for `NH_(3)` gas?

Explanation

`(P+(n^(2)a)/(V^(2)))V=nRT or, PV=nRT-(n^(2)a)/(V)`
or, `(PV)/(nRT)=1-(na)/(VRT) or, Z=1-(na)/(VRT)=1-(2xxa)/(VRT)`
again, `Z=(PV)/(nRT)` or, `0.931=(9.31xxV)/(2xx0.0821xx300)`
`therefore V=4.99L`
`therefore 0.931=1-(2xxa)/(4.99xx0.0821xx300)` or,
`a=4.24L^(2)*atm*mol^(-2)`