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

Answer:

Mole fraction of methanol will be closest to 4.

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:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{128\ g}{32.04\ g/mol}$

$Moles\ of\ methanol = 3.995\ mol$

Given, Mass of water = 108 g

Molar mass of water = 18.0153 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{108\ g}{18.0153\ g/mol}$

$Moles\ of\ water= 5.995\ mol$

So, according to definition of mole fraction:

$Mole\ fraction\ of\ methanol=\frac {n_{methanol}}{n_{methanol}+n_{water}}$

$Mole\ fraction\ of\ methanol=\frac{3.995}{3.995+5.995}=0.39989$

Mole fraction of methanol will be closest to 4.