Chemistry Class 12 NCERT Solutions: Chapter 2 Solutions Part 3

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Q: 7. Henry's law constant for in water is Pa at . Calculate the quantity of in mL of soda water when packed under atm pressure at .


It is given that:

According to Henry's law:

We can write,

is negligible as compared to ]

In of soda water, the volume of water

[Neglecting the amount of soda present]

We can write:

of water of water

Now, x

Hence, quantity of in 500 mL of soda water

Q: 8. The vapour pressure of pure liquids A and B are and mm Hg respectively, at K. Find out the composition of the liquid mixture if total vapour pressure is mm Hg. Also, find the composition of the vapour phase.


It is given that:

From Raoult’s law, we have:

Therefore, total pressure,




Now, in the vapour phase

Mole fraction of liquid A

Ans, mole fraction of liquid