CHM 2045C Module 6 Sample Exam
Part M: Multiple Choice Sample Answers

710 torr

Explanation:
Patm = PT - h = 760 torr - 50 torr

Solution Reference:
Page 539, Gas Pressure

Charles

Explanation:
V = kT

Solution Reference:
Page 545, Charles's Law

P, V

Explanation:

Solution Reference:
Page 548, The General Gas Law

Explanation:
VN = VO x pressure factor x temperature factor. Why is the pressure factor less than one? Why is the temperature factor greater than one?

Solution Reference:
Page 548, The General Gas Law

Explanation:
V = 75 mL x temperature factor x pressure factor. The temperature factor should be less than one. Why? The pressure factor should be greater than one. Why?

Solution Reference:
Page 548, The General Gas Law

The pressure will increase by a factor less than five.

Explanation:
Remember to convert the temperatures to the Kelvin scale. PN = PO x temperature factor x volume factor.

Solution Reference:
Page 548, The General Gas Law

18 x 22.4 L

Explanation:

Solution Reference:
Page 555, Gas Laws and Chemical Reactions

55.6 g/mol.

Explanation:
One mole = one gram molecular mass = 22.4 L at STP:

or use a derivation of PV = nRT.

Solution Reference:
Page 552, Density of Gases

C3H8.
Explanation:

Solution Reference:
Page 552, The Density of Gases

NF3
Explanation:

Solution Reference:
Page 552, Gas Densities

0.010

Explanation:
Use the equation PV = nRT. It doesn't matter what the gas molecules are.

Solution Reference:
Page 558, Gas Mixtures and Partial Pressures

0.040 moles

Explanation:

Solution Reference:
Page 558, Gas Mixtures

1.00 L of CO at 0.0?C and 1.25 atm

Explanation:
Look for a low temperature and a high pressure combination. Why?

Solution Reference:
Page 550, The Ideal Gas Law

The volume of the sample would be zero at -273?C.

Explanation:
Nitrogen has mass, and even though it will be frozen at absolute zero, it must of necessity have a volume.

Solution Reference:
Page 562, The Kinetic-Molecular Theory of Gases

is decreased by decreasing the kinetic energy of the gas molecules.

Explanation:
It only has a value of 22.4 L at 273 K and 1 atm pressure. The volume decreases with a decrease in temperature.

Solution Reference:
Page 562, Kinetic-Molecular Theory of Gases

1 : 1.

Explanation:
This question is testing a student's knowledge of Avogadro's law. At the same temperature and pressure, equal volumes of all gases contain the same number of molecules.

Solution Reference:
Page 562, The Kinetic-Molecular Theory of Gases

kinetic energy.

Explanation:
The kinetic energy of a gas depends upon temperature. At the same temperature, all gases have the same average kinetic energy.

Solution Reference:
Page 562, The Kinetic-Molecular Theory of Gases

when the temperature is increased and the pressure is decreased.

Explanation:
Most real gases approach ideal behavior at high temperatures and at low concentrations.

Solution Reference:
Page 571, Real Gases

High temperature and low pressure

Explanation:
Low concentrations and high kinetic energies (high temperatures).

Solution Reference:
Page 571, Real Gases

NH3

Explanation:
NH3 is a highly polar molecule. The dipole-dipole interaction between NH3 molecules is large enough that it is called hydrogen bonding.

Solution Reference:
Page 571, Nonideal Behavior

1 : 2.

Explanation:

Solution Reference:
Page 568, Diffusion and Effusion

1 to 1.

Explanation:
K.E. = 1/2 mv2. The kinetic energy changes with (and is proportional to) the absolute temperature.

Solution Reference:
Page 562, Kinetic-Molecular Theory of Gases

161/2 to 321/2.

Explanation:
Remember the inverse relationship.

Solution Reference:
Page 568, Diffusion and Effusion

Ar

Explanation:
All of the molecules have molecular masses less than that of "air" except Ar.

Solution Reference:
Page 570, Rubber Balloons