Interpretation:
The vapor pressure of pure A and pure B is to be calculated from the given moles of A and B and total vapour pressure.
Concept Introduction:
The pressure exerted by a solvent is equal to the product of that solvent’s mole fraction and the pressure exerted by the pure solvent. It is expressed as
Here,
The total pressure is calculated by the addition of partial pressure of A and partial pressure of B. It is expressed as
or
The mole fraction of compound can be calculated as
Answer to Problem 128AP
Solution:
Explanation of Solution
Given information: Moles of A:
Moles of B:
Total vapor pressure is
Total vapor pressure upon addition of another mole of B is
Calculate the mole fraction of A by using the expression given below:
Here,
Substitute
Calculate the mole fraction of B by subtracting the mole fraction of A from
The total pressure is calculated by the addition of partial pressure of A and partial pressure of B. It is expressed as
or
Substituting
Now, solving for
Now, consider the solution with the additional mole of B.
Calculate the mole fraction of A and B:
Substituting
Substituting Equation (2) into Equation (3) gives the equation below:
Substitute the value of
The vapor pressure of pure A and B is
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Chapter 13 Solutions
Chemistry
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