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An ideal solution was obtained by mixing...

An ideal solution was obtained by mixing methanol and ethanol. If the partial vapour pressure of methanol and ethanol are `2.619 kPa` and `4.556 kPa`, respectively, the composition of vapour (in terms of mole fraction) will be

A

0.635 methanol, 0.365 ethanol

B

0.635 methanol, 0.365 ethanol

C

0.574 methanol, 0.326 ethanol

D

0.173 methanol, 0.827 ethanol

Text Solution

Verified by Experts

The correct Answer is:
B
Method I : Trick
Ratio should be same of pressures and mole fractions which tally from option (b) i.e., 1 : 2.
Method II : Calculation
Partial pressure of methanol = 2.619 kPa .
Partial pressure of ethanol = 4.556 kPa .
Total pressure = partial pressure of methanol + partial pressure of ethanol
= 2.619 + 4.556 = 7.175 kPa
`chi_("methanol")=("Partial pressure of methanol")/("Total pressure")`
`=(2.619kPa)/(7.175kPa)=0.365`
`chi_("ethanol")=(4.556kPa)/(7.175kPa)=0.634`
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