LIVE Course for free

Rated by 1 million+ students
Get app now
0 votes
1.5k views
in Chemistry by (64.3k points)

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

1 Answer

+1 vote
by (66.3k points)
selected by
 
Best answer

Number of moles of H2O (n1) = {1000 g}/{18 g mol-1} = 55.55 mol.

Mole fraction of C2H5OH xC2H5OH = 0.04

xC2H5OH = {n2}/{n1 + n2} = {n2}/{55.55 + n2} = 0.04

n2 - 0.04 n2 = 55.55 x 0.04 = 2.222

0.96 n2 = 2.222

n2 = {2.222}/{0.96} = 2.31 mol

∴ Molarity of C2H5OH solution = 2.31 mol

Molarity of solution (M) = {No. of gram moles of C2H5OH}/{Volume of solution in litres}

In solution mass of H2O = 1000 g

Mass of C2H5OH = (2.31 mol) x (46 g mol-1) = 106.26 g

Total mass of the solution = 1000 + 106.26 = 1106.26 g

Density of ethanol = 0.800 g cm-3

Volume of the solution = {1106.26 g}/{0800 g cm-3} = 1382.8 cm3

Molarity of solution = {2.31 mol}/{(1382.8/1000) dm3} = {2.31 x 1000}/{1382.8} = 1.67 M

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...