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storm10
Aug 4, 2010, 03:55 PM
You are comparing two unknown liquids of similar molecular mass.
Liquid A has a vapor pressure that is much higher than that of liquid B at the same temperature. Which of the following is the most
Likely explanation for this observation.

A. Liquid B is nonpolar and liquid A is polar, and the stronger intermolecular forces in liquid A give the liquid a
Higher vapor pressure.

B. Liquid B is polar and liquid A in nonpolar, and the stronger intermolecular forces in liquid B give the liquid a lower
Vapor pressure.

C. Both liquids are nonpolar.

D. Both liquids are equally polar.

DrBob1
Aug 4, 2010, 05:35 PM
Storm:
We want to hear your views on this subject -- what do you think the answer is?
But here are some hints, or some food for thought:
What effect does polarity have on boiling and melting points of compounds?
Think of some compounds with similar molecular weights (for instance an alcohol and a hydrocarbon) Which ones are polar, which ones are nonpolar? Which ones boil higher than the others?
Think it over and give us your answer.

storm10
Aug 4, 2010, 06:44 PM
A more polar molecule will have a higher melting point. A polar molecule will have a strong dipole-dipole bond and will require more energy to break that bond.

Examples of polar molecules include ammonia and sugar . Polar molecules are generally able to dissolve in water due to the polar nature of water. Polar molecules have slightly positive and slightly negatively charged ends.

Non-polar molecules

Examples of non-polar compounds include fats, oil and petrol. Most non-polar molecules are water insoluble at room temperature. However many non-polar, such as turpentine, are able to dissolve non-polar substances.

DrBob1
Aug 4, 2010, 07:29 PM
Right on!
So how do you think this relates to your question? Why does liquid A have a much higher vapor pressure than liquid B? Remember the two compounds have similar molecular weights

Unknown008
Aug 5, 2010, 01:27 AM
This is correct. Now, on the thinking part, what do you think is your liquid A and liquid B?