The vapor pressures of ethanol (C2H5OH) and 1-propanol (C3H7OH) are 100 mmHg and 37.6 mmHg, respectively. Assume ideal behavior and calculate the partial pressures of ethanol and 1-propanol at 35 degrees Celsius over a solution of ethanol in 1-propanol, in which the mole fraction of ethanol is .300 .

I used the equation Pi = Xi * Ptotal. Where Pi is the partial pressure and Xi is the mole fraction.

So for ethanol I got Pi = .3 * 100mmHg = 30 mmHg (correct answer)

However for 1-propanol:
Pi = .3 * 37.6mmHg = 11.28 mmHg

But the book is telling me the answer is 26.3 mmHg.

Hellpp pleasee!

9 answers

And the book is right.
If the mole fraction for ethanol is 0.3, then the mole fraction for 1-propanol is 0.7 since mole fractions must add to 1.00.
THE MOLE FRACTION OF THE SOLUTES YIELD AT 1. THEREFORE IF ETHANOL HAS THE MOLE FRACTION OF 0.300, THE MOLE FRACTION OF 1-PROPANOL SHOULD BE 0.700 THEN USE THE EQUETION:Pi=Xi*P
=0.700*37.6mmHg
=26.32mmHg
26.32
This question is very easy guys , it doesn't need teachers guide 😂😂 just look at the problem carefully the mole fraction of 1-propanol= 1-0.3 =0.7 (because the question says ........over the solution) hence we calculate mole fraction of 1-propanol depending on that of ethanol.
The vapour pressure of ethanol (C2
H5
OH) and 1-propanol (C3
H7
OH) at 35°C are
100 mmHg and 37.6 mmHg, respectively. Assuming ideal behaviour, calculate the
partial vapour pressures of ethanol and 1-propanol over a solution, in which the
mole fraction of ethanol is 0.3
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