2. the Property of a Liquid That Measures Its Resistance to Flow Is Called ______

January 11

1. The phenomenon in which a steel needle can, with proper care, be made to float on the surface of some water illustrates a property of liquids know as

______.

2. The property of a liquid that measures its resistance to flow is called ______.

3. Which probably has the highest boiling point at 1.00 atm pressure?

H2NCH2CH2NH2, CH3CH2CH2NH2, (CH3)3N, CH3CH2NHCH3

4. Answer the questions for the following set of compounds:

NH3, H2O, HF, CH4, HBr

a) which compound(s) could exhibit hydrogen bonding?

b) which compound(s) could interact with another dipole?

c) which compound(s) exhibit only dipole-dipole and dispersion interactions?

d) which compound(s) exhibit only dispersion forces?

e) which compound would have the highest boiling point?

5. The factor that will have the largest effect on vapor pressure is:

a) liquid surface area

b) molecular dipole moment

c) presence of H-bonding

d) liquid molecular weight

e) volume available to the vapor

1. The phenomenon in which a steel needle can, with proper care, be made to float on the surface of some water illustrates a property of liquids know as surface tension.

2. The property of a liquid that measures its resistance to flow is called viscosity.

3. Which probably has the highest boiling point at 1.00 atm pressure?

H2NCH2CH2NH2, CH3CH2CH2NH2, (CH3)3N, CH3CH2NHCH3

The first one is about the same length as 2 and 4, but it’s the only choice that has two different places that you can hydrogen bond. The 3rd one doesn’t have a H attached to a nitrogen, so it can’t H-bond at all.

4. Answer the questions for the following set of compounds:

NH3, H2O, HF, CH4, HBr

a) which compound(s) could exhibit hydrogen bonding?

NH3, H2O, HF can all hydrogen bond to both themselves and other molecules that have a H on an F, O or N.

b) which compound(s) could interact with another dipole?

This is actually a bit of a trick question, since really all of them can if you induce a dipole in methane. But since your book only touches on three basic types of IMFs, then your answer should be all of the molecules except for CH4 can interact with another dipole.

c) which compound(s) exhibit only dipole-dipole and dispersion interactions?

HBr molecules will be held together with other HBr molecules by dipole-dipole interactions. The dispersion forces are there, but they are weak enough that they get ruled out by all of the other forces present. Since HBr can’t H-bond, the only other force is dipole- dipole.