Question

the mole fraction of c2h5oh in 5 molal aqueous ethyl alcohol solution is

Answer 1

Mole fraction of C2H5OH = Moles of ethanol / moles of ethanol + moles of water
                                          = 5 / 5+55.5
                                          = 5/60.5
                                          = 0.08

And thus mole fraction of water = 1- 0.08
                                                  = 0.92

Answer 2

Given:

The molality of ethyl alcohol solution = 5m

To find:

The mole fraction of C₂H₅OH

Solution:

For a binary solution having components A and B,

Mole fraction of A = No. of moles of A / (No. of moles of A + No. of moles of B)

Mole fraction of B = 1 - Mole fraction of A

5m ethyl alcohol solution means there are 5 moles of C₂H₅OH in 1000g water.

No. of moles of water = Given mass / Molar mass

= 1000/18 = 55.5 moles.

The mole fraction of C₂H₅OH = 5 / 5 + 55.5

= 5/ 60.5

= 0.08.

Hence, the mole fraction of C₂H₅OH is 0.08.