JEE MAIN - Chemistry (2020 - 7th January Morning Slot - No. 19)
At 35oC, the vapour pressure of CS2
is 512 mm. Hg and that of acetone is 344 mm Hg. A solution
of CS2
in acetone has a total vapour pressure of 600 mm Hg. The false statement amongst the
following is :
CS2 and acetone are less attracted to each other than to themselves.
a mixture of 100 ml. CS2 and 100 ml. acetone has a volume < 200 ml.
Heat must be absorved in order to produce the solution 35oC
Raoult's law is not obeyed by this system.
Explanation
As the vapour pressure of mixture increases so the force of attraction of mixture is less than the individual component.
Since the vapour pressure of the solution is greater than individual vapour pressure of both pure components, the solution shows a positive deviation from Raoult’s law.
$$ \therefore $$ $$\Delta $$SolH $$>$$ 0
As $$\Delta $$SolH $$>$$ 0 then solution is endothermic.
and here $$\Delta $$Sol Volume $$>$$ 0. As $$\Delta $$Sol Volume $$>$$ 0 then a mixture of 100 ml. CS2 and 100 ml. acetone has a volume more than 200 ml. It happens because the distance between molecules increases due to force of attraction of mixture decreases.
Since the vapour pressure of the solution is greater than individual vapour pressure of both pure components, the solution shows a positive deviation from Raoult’s law.
$$ \therefore $$ $$\Delta $$SolH $$>$$ 0
As $$\Delta $$SolH $$>$$ 0 then solution is endothermic.
and here $$\Delta $$Sol Volume $$>$$ 0. As $$\Delta $$Sol Volume $$>$$ 0 then a mixture of 100 ml. CS2 and 100 ml. acetone has a volume more than 200 ml. It happens because the distance between molecules increases due to force of attraction of mixture decreases.
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