Question

We have 10% w/w aq. solution of NaOH Find:
Molality molarity and mole fraction

Answer 1

The solution is in the attachment.

Answer 2

Explanation:

CHEMISTRY

Aqueous solution of NaOH is marked 10%(w/w). The density of the solution is 1.070gcm

−3

Calculate:

(i) molarity

(ii) molality and

(iii) mole fraction of NaOH & water.

[Na=23,H=10,O=16]

December 26, 2019avatar

Vijaya Summaiya

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ANSWER

Here if an 100 g of an diluted NaOH solution is marked as 10%(w/w) of NaOH then W

2

(mass of solute)=10g and mass of water(W

1

)=90g.

density=

V

solution

mass

V

solution

=

1.070

100

=93.46cm

−3

=0.09346L

number of moles of NaOH(n

solute

)=

49g(mol)

−1

10g

=0.2mol

Molarity=

V

solution

n

solute

Molarity=

0.09346L

0.2mol

=2.14M

molality=

W

1

(inkg)

n

solute

molality=

0.09kg

0.2mol

=2.22m

Let mole fraction of water and NaOH be x

1

and x

2

and n

1

and n

2

be the moles of water and NaOH

n

1

=0.2mol and n

2

=

18g(mol)

−1

90g

=5mol

x

1

=

n

1

+n

2

n

1

=0.96

x

2

=

n

1

+n

2

n

2

=0.04