Find the molalitiy of 12% HNO3 solution
Answers
Answer:
Let us consider that there is 100 grams of HNO
3
solution.
∴ Mass of HNO
3
+ Mass of H
2
O=100 g
∵ Mass of HNO
3
=12.2 g
∴12.2g+ Mass of H
2
O=100 g
∴ Mass of H
2
O=100−12.2=87.8 g
n
H
2
O
=
M
H
2
O
W
H
2
O
=
18
87.8
=4.87 mol
Number of moles of HNO
3
n
HNO
3
=
M
HNO
3
W
HNO
3
=
63
12.2
=0.1936 mol
∴ Total moles in the solution,
n
H
2
O
+n
HNO
3
=4.87+0.1936=5.06 mol
∴ Mole fraction of HNO
3
=
Total number of moles (in soln.)
No. of moles of HNO
3
=
5.06
0.1936
=0.0383
Now, Molality of HNO
3
=
Mass of solvent in gram
Moles of solute (HNO
3
)
×1000
=
87.8
0.1936×1000
=2.205 mol kg
−1
Hence, mole fraction and molality of HNO
3
, in a solution containing 12.2% HNO
3
is 0.0389 and 2.205 mol kg
−1
respectively