Question

Item 5 A solution of methanol, CH3OH, in water is prepared by mixing together 128 g of methanol and 108 g of water. The mole fraction of methanol in the solution is closest to

Answer 1

Mole fraction of methanol will be closest to 4.

Step-by-step explanation:

Given, Mass of methanol = 128 g

Molar mass of methanol = 32.04 g/mol

The formula for the calculation of moles is shown below:

`moles = (Mass\ taken)/(Molar\ mass)`

Thus,

`Moles= (128\ g)/(32.04\ g/mol)`

`Moles\ of\ methanol = 3.995\ mol`

Given, Mass of water = 108 g

Molar mass of water = 18.0153 g/mol

The formula for the calculation of moles is shown below:

`moles = (Mass\ taken)/(Molar\ mass)`

Thus,

`Moles= (108\ g)/(18.0153\ g/mol)`

`Moles\ of\ water= 5.995\ mol`

So, according to definition of mole fraction:

`Mole\ fraction\ of\ methanol=\frac {n_(methanol)}{n_(methanol)+n_(water)}`

`Mole\ fraction\ of\ methanol=(3.995)/(3.995+5.995)=0.39989`

Mole fraction of methanol will be closest to 4.