Self Test on States of matter, intermolecular forces, and gas laws

Short essay questions

1.	What is the origin of the earth's atmospheric pressure? What does the term "1 atmosphere" mean?

2.	Describe dipole-dipole forces and London forces. Describe how each arises. Tell which one is stronger. Give examples of molecules for both types of forces. molecule.

3.

Tell which type of interaction( dipole-dipole forces or London forces)exists between molecules in the following table. molecule type of intermolecular force molecule type of intermolecular force N2 ----------------------------------------------- CH3Cl ----------------------------------------------- CO2 ----------------------------------------------- SO2 -----------------------------------------------

4.	What is the reason that liquids have different normal boiling points? What is a "normal" boiling point? Do liquids only boil at the "normal" boiling point?

5.	What is meant by the term "vapor pressure"? Describe how intermolecular forces and temperature influence the vapor pressure of a substance.

6.	Do solids and liquids both show a vapor pressure? Explain

7.

Vapor pressure values for, CH3Br, methyl bromide are given in the table below. How do the intermolecular forces between methyl bromide, CH3Br, molecules compare with the strength of intermolecular forces between water, H2O molecules. Use the data for vapor pressures to support your answer. CH3Br, Temperature in oC vapor pressure in mm Hg -63oC 100 -38oC 400 -24oC 760

8.	Why does the ideal gas equation give the same volume for a mole of any gas? PV = nRT
	Does the Ideal gas law pay attention to the fact that molecules of methane CH4 and butane CH3CH2CH2CH3 havedifferent volumes?

9.

Which molecule in the following pairs has stronger intermolecular forces? Identify the types of forces present for each molecule, London forces, LF; dipole-dipole forces,DD; hydrogen bonding, HB. molecule pair types of intermolecular force molecule pair types of intermolecular force H2 or N2   ------------------------------------------------------------ CH3Cl or CH4   ------------------------------------------------------------ SO2 or CO2   ----------------------------------------------------------- H2O or H2S   ------------------------------------------------------------

Multiple choice

1.	Which of the following pairs of shows dipole-dipole forces.
	a. NaCl and HCl
	b. HF and H2
	c. H2 and H2
	d.HF and HF

2.	Which of the following exists as a covalent network solid.
	a. Cu
	b. NaCl
	c. CH4
	d.diamond, C

3.	How many mols of CO2 gas are in the following gas sample? V = 2.24 L ; P = 1.0 atm ; T = 310 K Recall PV = nRT; R = 0.0821 L atm/ mol K
	a. 0.0094 mol
	b. 0.094 mol
	c. 0.94 mol
	d. 0.000094 mol

4.	Which of the following displays hydrogen bonding.
	a. CH4
	b. CH3OH
	c. CH3OCH3
	d. CH3CH2CH2CH3

5.	What is the molar volume of an ideal gas at STP?
	a. it depends on the gas
	b. it is always 22.4 L
	c. it depends on the volume of the container
	d. cannot say the molecular formula is needed

6.	Which of the following substances has the lowest melting point?
	a. gold, Au
	b. sand, SiO2
	c. butane, CH3CH2CH2CH3 , C4H10
	d.water, H2O

7.	Which of the following gases has the lowest density?
	a. methane, CH4
	b. ethane, CH3CH3
	c. propane, CH3CH2CH3
	d. butane, CH3CH2CH2CH3

8.	Which of the following substances has the strongest London forces?
	a. methane, CH4
	b. ethane, CH3CH3
	c. propane, CH3CH2CH3
	d. butane, CH3CH2CH2CH3

9.	What is the final pressure for a gas that was initially at 0.95 atm at 25oC if the temperature is increased to 125oC?
	a. (0.95 atm)(298 K/398 K)
	b. (0.95 atm)(125oC/25oC)
	c. (0.95 atm)(25oC/125oC)
	d. (0.95 atm)(398 K/298 K)

10.	What is the final volume for a sample of oxygen, O2, that was initially at .65 atm at 25oC with a volume of 600 mL, if the pressure is increased to 0.85 atm at 25oC?
	a. (600 mL)(0.65 atm/0.85 atm); the volume goes down
	b. (600 mL)(0.85 atm/0.65 atm); the volume goes up
	c. (0.65 atm/0.85 atm) /(600 mL); the volume goes up
	d. the volume stays the same

11.	What is the pressure in atmospheres when the pressure is 440 mm Hg?
	a. (440)(760) b. (440)/(760) c. (760)/(440) d. 760 - 440

12.	What is the volume of 34 grams of H2 gas at STP?
	a. 22.4 L
	b. (22.4 L)x(34)
	c. (22.4 L)x(34)(1/2)
	d. N and O

13.	Which of the following is arranged in order of increasing boiling points.
	a. Kr, Ne, He
	b. Br2, F2, Cl2
	c. H2Se, H2S, H2O
	d. H2O, He, N2

14.	Which of the following will have stronger London forces.
	a. H2
	b. He
	c. Ne
	d. Kr

15.	Which of the following molecules shows the greatest effects of hydrogen bonding?
	a. H2S
	b. CH4
	c. NH3
	d. H2O

  Online Introductory Chemistry

Dr. Walt Volland,