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  • The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively, at 350 K. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.

The vapour pressure of pure liquids A an | Class 12 Chemistry Chapter Solutions, Solutions NCERT Solutions

Q8.

The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively, at 350 K. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.

It is given that:

PAo = 450 mm of Hg

PBo = 700 mm of Hg

ptotal = 600 mm of Hg

From Raoult's law, we have:

ptotal = PA + PB

 

Therefore, xB = 1 - xA

= 1 - 0.4

= 0.6

 

Now,  PA = PAo xA

= 450 × 0.4

= 180 mm of Hg

and PB = PBo xB

= 700 × 0.6

= 420 mm of Hg

Now, in the vapour phase: Mole fraction of liquid A =  PA / (PA + PB )

=180 / (180+420)

= 180/600

= 0.30

And, mole fraction of liquid B = 1 - 0.30

= 0.70

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Important Questions & Answers

What is the correct answer to: The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively, at 350 K. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.?

It is given that:

PAo = 450 mm of Hg

PBo = 700 mm of Hg

ptotal = 600 mm of Hg

From Raoult's law, we have:

ptotal = PA + PB



 

Therefore, xB = 1 - xA

= 1 - 0.4

= 0.6

&nb...

How do you solve The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively, at 350 K. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase. step by step?

Step-by-step explanation:
• It is given that:

• PAo = 450 mm of Hg

• PBo = 700 mm of Hg

Why is this answer important for exams?

This question is important because it tests key concepts from the NCERT syllabus and is frequently asked in CBSE exams.

Which NCERT concept is used in this question?

This question is based on core NCERT concepts explained in the chapter and should be revised thoroughly before exams.

What common mistakes should be avoided in this question?

Students often lose marks by skipping steps, writing incomplete explanations, or misunderstanding keywords used in the question.

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Student Discussion

Bhavesh
Class · · , · Oct 14, 2019
Aneesha ,what you have a doubt is another representation of the same formula😂.
p(total)=p(a)+p(b) which is p°(a)x(a)+p°(b)x(b)
But we also know that sum of mole fractions is 1 x(b)=1-x(1)
Deducing it we get the simpler form
👍 👎 Reply
Lia
Class · · , · Jun 18, 2019
Similar doubt as that of anisha's
👍 👎 Reply
Tayaba
Class · · , · May 13, 2019
What does it mean by composition ? Either it mean mole fraction or vapour pressure ?
👍 👎 Reply
rahul
Class · · , · Apr 24, 2019
the query of aneesha is a poor one...
Ask something good baby...
👍 👎 Reply
Shivam
Class · · , · Jun 12, 2018
It ask for composition. In your answer you give partial vp so it means composition means partial vapour pressure.
👍 👎 Reply
Aneesha
Class · · , · Mar 25, 2018
Hello. I have a small query.
By using the formula P(total)=P(A)+[P(B)-P(A)]X(B), we get the value of X(B) as 0.42 and X(a) as 0.58. If done in this way, we end up multiplying 450 with 0.58 and 700 with 0.42. Why then am i ending up in the reverse order ? (the formula is given in the NCERT textbook-in terms of 1 and 2 instead of A and B)
👍 👎 Reply

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