Chapter 11: Gases

Question 1

List the five postulates of kinetic-molecular theory of gases

Answer 1

1. Particles are not attracted to each other or its container
2. Are always in motion and moves in a straight line but random movement
3. When they strike each other, energy is conserved, not lost
4. Kinetic energy increases when temperature increases
5. the temp is the average kinetic energy of the particles

Question 2

Explain the physical properties of gases using concepts from the kinetic-molecular
theory

Answer 2

Gases are compressible, the particles can be moved closer together. The shape equals the shape of their container, expand to fill the whole container. Gasses have low density

Question 3

Define (gas) pressure.

Answer 3

frequency that the gases strike the surface, the wall of the container.

Question 4

Remember the conversion between units of pressure.

Answer 4

1 atm = 760 mm Hg = 760 torr.
These are exact conversions, so they will not influence the number of significant figures.

Question 5

Remember the USA measure of pressure.

Answer 5

atmospheric pressure as inches of
mercury (in Hg) and to measure tire pressure as pounds per square inch (psi).

Question 6

Remember the conversion factor used to convert between the Celsius and Kelvin
temperature scales.

Answer 6

(EC + 273 = K or K – 273 = EC)

Question 7

For any gas calculation question using temperature (see below), only Kelvin temperature
is used. Explain the reason.

Answer 7

zero on the kelvin scale refers to stop of molecular motion

Question 8

List the four factors that affect the behavior (activity) of gases.

Answer 8

Pressure, temperature, volume, and number of particles (mol)

Question 9

The relationships between two variables associated with gases are described by individual gas laws

Answer 9

Boyle’s Law: P x V = k
Charles’ Law: V/T = k
Gay Lussac’s Law: P/T = k
Avogadro’s Law: V/n = k

Question 10

Remember the combined gas law equation with eight variables.

Answer 10

(P1 x V1) / (T1 x n1) = (P2 x V2) / (T2 x n2). When a variable in condition 1 does not change in condition 2

Question 11

Remember the ideal gas law

Answer 11

PV - nRT when R is constant = (0.0821 x L) / (mol x k)

Question 12

Remember Dalton’s Law of Partial Pressures

Answer 12

the total pressure in a container is equal to the sum of the individual gas pressures. The different gas pressures are proportional to the total amount of gas

Question 13

Explain how the gas pressure in a container is affected

Answer 13

Pressure decreases when volume increases. Pressure increases when temperature increases. Pressure increases when number of molecules increase

Question 14

Explain how the gas pressure in a container is affected by changes in container volume

Answer 14

decreasing volume increases gas pressure

Question 15

Explain how the gas pressure in a container is affected by changes in temperature

Answer 15

increasing temperature increases gas pressure

Question 16

Explain how the gas pressure in a container is affected by changes in the moles of gas molecules present

Answer 16

increasing gas molecules increases pressure