Answer:
0.7681
Explanation:
Given that the mass percentage of methanol = 85.5 %
which means that 85.5 g of methanol is present in 100 g of the solution.
Thus, mass of water = 100 g - 85.5 g = 14.5 g
The formula for the calculation of moles is shown below:
[tex]moles = \frac{Mass\ taken}{Molar\ mass}[/tex]
Mass of methanol = 85.5 g
Molar mass of methanol = 32.04 g/mol
Moles of methanol = 85.5 g / 32.04 g/mol = 2.6685 moles
Mass of water = 14.5 g
Molar mass of methanol = 18 g/mol
Moles of methanol = 14.5 g / 18 g/mol = 0.8056 moles
So, according to definition of mole fraction:
[tex]Mole\ fraction\ of\ methanol=\frac {n_{methanol}}{n_{methanol}+n_{water}}[/tex]
Applying values as:
[tex]Mole\ fraction\ of\ methanol=\frac {2.6685}{2.6685+0.8056}[/tex]
Mole fraction of methanol in the solution = 0.7681
