Question

1.25 g of a mixture of Na2Co3 and Na2so4, is
present in 250 ml aqueous solution. 25 ml of this solution is
completely neutralised by 20 mL of 0.1 N H2So4. Calculate
the % composition of the mixture.​

Answer 1

Answer:

Correct option is

A

84.8%

The equivalent weight of Na

2

CO

3

is 53.

Let the amount of Na

2

CO

3

present in the mixture be x g. Na

2

SO

4

will not react with H

2

CO

3

.

Then, the number of gram equivalents of Na

2

CO

3

= the number of gram equivalents of H

2

SO

4

.

53

x

=

1000

20×0.1×10

∴x=1.06g

Note: We have divided with 1000 to convert the volume of H

2

SO

4

from mL to L.

We have multiplied with 10 as out of 250 mL of Na

2

SO

4

solution, only 25 mL is used for neutralisation with H

2

SO

4

25

250

=10

The number of gram equivalents of H

2

SO

4

are obtained by multiplying volume with normality.

The percentage of Na

2

CO

3

=

1.25

1.06×100

=84.8%