74 An unknown solution X has a molar mass of 17, molarity of 15.2 M and density of 0.8980 g/ml. Calculate the mole fraction of X
Ops: A.
B.
1.268
0.326
0.299
O
D.
0.122
Answers
Answered by
0
Answer:
Given that
x
B
=0.2,x
A
=0.8
Now,
Molality (m)=
x
A
×M
A
x
B
×1000
=
0.8×18
0.2×1000
=13.88m
where,
M
A
= molar mass of solvent
Answered by
4
Given:
M.wt = 17 gm
M = 15.2 M
d = 0.898 g/ml
To Find:
The mole fraction of X.
Calculation:
- Molarity = (10 × d × wt%)/M.wt
⇒ wt % = (M × M.wt)/(10 × d)
⇒ wt % = (15.2 × 17)/(10 × 0.8980)
⇒ wt % = 258.4/8.98 = 28.775
- Let the mass of the solution be 100 gm.
⇒ Mass of X = 28.775 gm
& Mass of water = 71.225 gm
- No of moles of X, n1 = 28.775/17 = 1.693
- No of moles of water, n2 = 71.225/18 = 3.957
- Total no of moles = n1 + n2
⇒ N = 1.693 + 3.957 = 5.65
- Mole fraction of X = n1/N
⇒ X = 1.693/5.65
⇒ X = 0.299
- So, the correct option is (c) 0.299
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