Question

What will be the value of P°B if total pressure of the solution is given by Ptotal = 75 + 150XB mm of Hg

Answer 1

Answer:

Explanation:To find: Vapour pressure of pure B

When XA =0,we have pure B

So, PB*=75+150(1-XA)

=75+150=225

Answer 2

Answer:

225 mmHg

Explanation:

Given: Ptotal = 75 + 150 XBmmHg

To find: P°B

Solution:

Ptotal = P°A XA + P°B XB ........... equation 1

XA + XB = 1

So, XA = 1 - XB

Now, we put the value of XA = 1 - XB in equation 1.

Ptotal = P°A (1 - XB) + P°B XB

Ptotal = P°A - P°A XB + P°B XB

Ptotal = P°A + XB (P°B - P°A) .......... equation 2

On eqauting equation 1 and 2 and put the value of Ptotal = 75 + 150 XBmmHg , we get,

75 + 150 XB = P°A + XB (P°B - P°A) = 0

P°A = 75

P°B - P°A = 150

On putting the value of P°A = 75, we get,

P°B - 75 = 150

Therefore, P°B = 150+75 = 225 mmHg

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