Test Index

NCERT Class XII Chemistry
Chapter - Solutions
Questions with Solutions

© examsnet.com
Question : 5
Total: 53
A solution of glucose in water is labelled as 10% w/w. What would be the molality and mole fraction of each component in the solution? If the density of the solution is 1.2 g mL‌–1, then what shall be the molarity of the solution?
Solution:  
Let mass of solution = 100 g
∴ Mass of glucose = 10 g
Mass of water = 90 g = 0.09 kg
No. of moles in 10 g glucose =
10
180
 = 0.0555 mol
No. of moles in 90g H2O =
90
18
 = 5 moles
Volume of solution =
100g
1.2gmL−1
 = 83.33 mL = 0.0833 L
(a) Molality =
Number of moles of solute
Mass of solvent in kg
 =
0.0555‌mol
0.09‌kg
 = 0.617 m
(b) x (Glucose) =
Number of moles of solute
Number of moles of solution
=
0.0555
5.0555
 = 0.01
∴ x (H2O) = 1 – 0.01 = 0.99
(c) Molarity =
Number of moles of solute
Volume of solution in L
 =
0.0555
0.0833
 = 0.666 M
© examsnet.com
Go to Question:
Prev Question
Next Question