PLEASE HELP! thank you sooo much! 10. You are given the following boiling point

Question

PLEASE HELP! thank you sooo much!

10. You are given the following boiling point data. Which one of the liquids would you expect to have the highest vapor pressure at room temperature?

A) water, H2O --->100°C B) methanol, CH3OH ---->64.96°C C) ethanol, CH3CH2OH ---->78.5°C D) diethyl ether, CH3OH2–O–CH2CH3 ----> 34.5°C E) ethylene glycol, HO–CH2–CH2–OH ---->198°C

12. Knowing that DHvap for water is 40.7 kJ/mol, calculate Pvap of water at 58°C.

A) 5.3 torr B) 456 torr C) 14.8 torr D) 759 torr E) 144 torr

Thank you again for helping me!

Explanation / Answer

10)
lesser the boiling point, there will more vapour pressure
boiling point is least for diethyl ether
so, vapour pressure is maximum for diethyl ether

Answer: D

12)
boiling point is 100 oC
Pressure at this temperature is 760 torr

T1 = 100 oC = (100 + 273) K =373 K
P1 = 760 torr

T2 = 58 oC= (58 + 273) K= 331 K
P2 = ?

ln (P2/P1) = (DHVap/R)*(1/T1 - 1/T2)
ln (P2/760) = (40700/8.314)*(1/373 - 1/331)
ln (P2/760) = -1.665
P2/760 = 0.189
P2 = 144 torr

Answer: E

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