a solution of 0.6216 g of an unknown solute in 50g of ccl4 yields a Bp of elevation of 0.647c find the molecular mass of the unknown solute if the molal elevation constant is 5.02k????
Answers
Answer:
12th
Chemistry
Solutions
Colligative Properties and Determination of Molar Mass
A solution containing 0.5 g...
CHEMISTRY
A solution containing 0.5 g of naphthalene in 50 g CCl
4
yield a boiling point elevation of 0.4 K, while a solution of 0.6 g of an unknown solute in the same mass of the solvent gives a boiling point elevation of 0.65 K. Find the molar mass of the unknown solute.
HARD
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ANSWER
Napthlene C
10
H
8
,M=12×10+8=128g
Molality of Naphthalene in CCl
4
, m=
128
0.5
×
50
1000
ΔT
b
=K
b
m
0.4=K
b
128
0.5
×
50
1000
...(i)
Let the molar mass of unknown solute be M.
The molality of unknown solute in CCl
4
, m=
M
0.6
×
50
1000
ΔT
b
=K
b
m
0.65=K
b
×
M
0.6
×
50
1000
...(ii)
Divide equation (i) by (ii)
0.65
0.4
=
0.6×128
0.5×M
M=
0.65×0.5
0.4×0.6×128
=94.523
Explanation: