The vapour pressures of pure benzene and toluene at 25°C are 95 mmHg and 29 mmHg respectively — JEE Chemistry
The vapour pressures of pure benzene and toluene at 25°C are 95 mmHg and 29 mmHg respectively. Find the total vapour pressure of an equimolar ideal solution.
1 Answer
VCVarun Choudhary
✓ Accepted
· 2mo ago
▲ 36
Mole fraction of each = 0.5
$$P_{total} = x_A P_A^° + x_B P_B^° = 0.5 \times 95 + 0.5 \times 29 = 47.5 + 14.5$$
$$P_{total} = 62 mmHg$$
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Discussion (5)
A
Quick doubt: would this method still work if the numbers were not so clean?
TS
How do we know the approximation is valid here?
K
I solved it a slightly different way and got the same answer, good sign.
AS
Is there a faster shortcut for this in the actual exam? Time is tight.
VA
Good follow-up questions — remember to always state your assumptions in the JEE subjective section.