Question

Calculate the molarity of a solution of ethanol in water in which the molar fraction of ethanol is 0.040

Answer 1

Answer:

The mole fraction of ethanol is equal to the ratio of the number of moles of ethanol to the total number of moles present in the solution.

For dilute solutions, 1 L of water (or 1 L of solution) contains

18

1000

=55.55 moles of water.

Let n be the number of moles of ethanol. The mole fraction of ethanol is 0.040.

Hence, 0.040=

n+55.55

n

n=0.040n+2.222

n=

1−0.040

2.222

=2.31 moles.