Question

Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040 (density of water = 1)

Answer 1

Mole fraction of ethanol is given that is 0.040 (X)
As in this case ethanol acted as solute
X= n2(ethanol)/n2(ethanol)+n1(no.of moles of water)
As the solution is diluted tus
1lt of soln=1lt of water
n1(number of moles of water)= 1000g/18=55.5
By putting this in formula
0.040=n2(ethanol)/n2+55.5
By taking reciprocal of this
25=1+55.5/n2
25-1=55.5/n2
24=55.5/n2
n2=2.31
Thus, in 1000g of water contains 2.31 moles of ethanol
Therefore,the molarity of solution is 2.31M.