Question

Calculate the number of moles of methanol in `5` litres in its `2m` solution, if the density of the solution `0.981kgL^(-1)` (molar mass of methanol `=32g "mol"^(-1)`)

Answer 1

Correct Answer - `9.22` moles.
`nXH_(3)OH=?`
Mass of solution `=` Volume of solution `xx` density of solution
Mass of solution `=5Lxx0.981kg l^(-1)=4.905kg=4905g`
Mass of solute`=2xx32=64g`.
Mass of `2m` solution containing `1kg` of solvent `=64+1000=1064g`.
`4905g` of solution contains `=(2 "moles")/(164)xx4905=9.22` moles of methanol.