Question

ethanol is 0.040 (assume the density of water to be one).
Calculate the molarity of a solution of ethanol in water.​

Answer 1

Answer:

Explanation:

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.

The molarity of the solution is the ratio of the number of moles of solute present in 1 L of solution.

As 1 L of solution contains 2.31 moles of ethanol, the molarity of a solution is 2.31 M.