How would you determine molar mass from relative lowering of vapour pressure.

Explanation

According to van.t Hoff equation
`pi = CRT`
`C = n /V`
Here n = number of moles of solute dissolved in .V. litre of the solution.
`therefore pi = n/V RT implies pi V = nRT`
If the solution is prepared by dissolving `W_(B)` of the non-volatile solute in `W_(A)` g of solvent, the the number of moles of .n. is
`n = (W _(B))/(M _(B)) ` where, `M _(B)=` molar mass of the solute
Substituing n value, we get
`pi = (W _(B))/(V) . (RT)/( M _(B))`
`M _(B) = (W_(B))/(V). (RT)/(pi)`
From the above equation, we can calculate the molar mass of the solute.