Test Index

NCERT Class XI Chemistry Some Basic Concepts of Chemistry Solutions

© examsnet.com
Question : 29
Total: 36
Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040.
Solution:  
xC2H2OH =
nC2H5OH
nC2H5OH+nH2O
 = 0.40 (Given) ... (i)
The aim is to find number of moles of ethanol in 1 L of the solution which is nearly = 1 L of water (because solution is dilute)
Number of moles of water in 1 L of water =
1000g
18gmol−1
 = 55.55 moles
Substituting nH2O = 55.55 in eqn (i), we get
nC2H5OH
nC2H5OH+55.55
 = 0.040
or 0.96 nC2H5OH = 55.55 × 0.040 or nC2H5OH = 2.31 mol
Hence, molarity of the solution = 2.31 M.
© examsnet.com
Go to Question:
Prev Question
Next Question