Chapter Five-Gases and Atmospheric Chemistry

Question 0

Particles are able to move independently on one another. Particles in a gaseous move in Translational Motion. Explain.

Answer 0

Particles in a gaseous state are able to move independently of one another. Gas particles are able to move from one point in space to another, Translational Motion. Particles of gas move in all three motions, Translational, Rotational and Vibrational, resulting in a high degree of disorder. This is because particles move through space randomly in straight lines (altered by collision), forces flow in all directions and are not affected by gravity as heavily as liquids and solids are.

Question 1

Particles of solids and liquids are incompressible, and therefore have a definite volume. Why do solid particles move in one motion, while liquid particles move in two simultaneously?

Answer 1

Particles of a solid are held in a crystal lattice structure; this means that the positions are fixed and restricted. Each particle of a solid is only able to vibrate around a fixed point, this is called Vibrational Motion. Liquid particles, however, move more freely than those of a solid, though not independently. Liquid particles move in Vibrational Motion, as well as rotate and change position, Rotational Motion. Moving in these two motions explains liquids ability to flow and change shape while keeping volume.

Question 2

Describe Ionic Attraction.

Answer 2

Ionic bonding is one example of electrostatic attration. A positive ion is attracted to a negative ion. These ions form strong ionic bonds. In nature, these exist as solids (crystalline lattice structure) and they have high melting and boiling points. Ex: NaCl

Question 3

Describe Polar (Dipole-Dipole) Attraction.

Answer 3

Intermolecular forces are forces that exist between neutral molecules or molecules and ions. Some molecules are polar due to asymmetrical shape (SO2) leading to one end to be slightly more positive and one end to be slightly more negative; creating a permanent dipole effect. In nature these exist as liquids or gases. Ex. HCl, Ethanol

Question 4

What is the relationship between size and state?

Answer 4

The state of a substance depends on the forces between the particles of that substance. If the forces are very strong, the substance is a solid. If the forces are very weak, the substance is a liquid or a gas. Smaller non-polar molecules are more likely to be gases (CH4, low boiling point) and large non-polar particles will probably exist as liquids or solids (C5H12, high melting point). This is due to surface area, volume, attraction and kinetic energy.

Question 5

Describe Dispersion Attraction.

Answer 5

Weak dispersion forces form between non-polar molecules. This leads temporary dipoles to form, causing molecules to come closer together. However, these are weak and temporary bonds and do not hold for long. In nature, these are gases. Ex. CO2

Question 6

Describe the process of Condensation.

Answer 6

Condensation of a gas occurs when particles are compressed and the space tightens between the gas particles. This creates a liquid.

Question 7

Will a hotter or a cooler substance have more Ek?

Answer 7

A hotter substance will have higher Ek, and is more likely to overcome attractive forces between molecules and exist as a gas because movement increases. Ex. Boiling H2O
A cooler substance will have lower Ek, and is more likely to be a solid or liquid.

Question 8

What happens when a solid is heated?

Answer 8

When a solid is heated it gains Ek, in some cases causing a change in state.

Question 9

Which state has the quickest particles?

Answer 9

Gas particles move more quickly than liquids or solids because of their higher Ek. Ex. C2 has no attraction between particles and that is why it has such fluid movements.

Question 10

True or False. The volume of an individual gas molecule is negligible in relation to the volume of the gas container; gas molecules have no volume of their own because the container is mostly ‘occupied’ space.

Answer 10

False.

…the container is mostly ‘empty’ space.

Question 11

True or False. There is an abundance of attractive and repulsive forces between gas molecules.

Answer 11

False.

…there are no attractive or repulsive forces between gas molecules.

Question 12

Fill in the blank. Gas molecules have a ____________ translational energy. They move _______________ in all directions in _______________ lines.

Answer 12

A) high
B) randomly
C) straight

Question 13

True or False. When gas molecules collide with each other or a container, collisions are perfect elastic and there is no loss of Ek.

Answer 13

True.

Like billiard balls.

Question 14

Fill in the blanks. Average Ek _____________ with temperature.
__________ temperature, higher motion, ____________ average Ek.

Answer 14

A) is in direct relation
B) higher
C) higher

Question 15

True or False. An ideal gas is a gas in which the particles take up hardly any space and do not attract each other.

Answer 15

True.

Question 16

Fill in the blanks. Nearly all gases behave in __________ and predictable ways. The properties and ______________ of real gases can be generalized into a theory of an ideal gas. ______ gas is ‘ideal’, the theory neglects certain facts about _______ gases like they don’t take up ___________, but particles of matter must take up space.

Answer 16

A) similar
B) behaviours
C) No
D) real
E) space

Question 17

Define Pressure.

Answer 17

Force exerted on an obejct, per unit of surface area.

Question 18

How does a gas exert pressure?

Answer 18

Think of blowing up a basketball. As you add air, more molecules collide against the inside wall, each collision exerting a force on the basketball’s inner surface area. The total number of collisions and the strength of the force form the net or overall gas pressure. Since molecules move in all directions, the net pressure exerted will be equal throughout.

Question 19

Define Atmospheric Pressure.

Answer 19

The pressure exerted by the weight of the atmosphere.

Question 20

What are these?

760 mmHg=760 torr=1 atm= 101.3 kPa

Answer 20

Unitary rates used to measure pressure.

Question 21

State Boyle’s law and its formula.

Answer 21

As EXTERNAL PRESSURE on a gas INCREASES, the VOLUME of the gas DECREASES by the same factor.
Formula:
P1V1=P2V2
*this is true for all gases as long as the temperature remains unchanged

Question 22

State Charles’ law and its formula.

Answer 22

The VOLUME of a fixed mass of gas is PROPORTIONAL to its Kelvin temperature when the PRESSURE is kept constant.
Formula:
V1=V2
T1 T2

Question 23

State Gay-Lussac’s law.

Answer 23

The pressure of a fixed amount of gas, at a constant volume, is directly proportional to its Kelvin temperature.
P1=P2
T1=T2

Question 24

Fill in the blanks.
Boyle’s law solves for changes in __________ when pressure changes (constant T)
___________ solves for changes in VOLUME when temperature changes (constant P)
Gay-Lussac’s Law solves problems where ____________ and ___________ change (constant V)

Answer 24

A) Pressure
B) Charles’ Law
C) Pressure
D) Temperature

Question 25

What is the formula for combined gas law?

Answer 25

P1V1=P2V2

T1 T2

Question 26

What is standard pressure and temperature?

Answer 26

101.3 KPa and 273K

Question 27

What is SATP?

Answer 27

25C and 100KPa

Question 28

What is Dalton’s Law of Partial pressure?

Answer 28

Total pressure of a mixture of gases is the sum of pressures of each of the individual gases.

Question 29

Through the Law of Combining Volumes and the Law of Multiple Proportions, what did Avogadro come up with?

Answer 29

Equal volumes of all ideal gases (same T and P) contain the same number of molecules therefore
n1=n2
v1 v2

Question 30

State Avogadro’s Law.

Answer 30

One mole of a gas occupies the same volume as one mole of another gas (same T and P).

Question 31

Define Molar Volume.

Answer 31

Is the space that is occupied by one mole of a gas (L/mol).

NOTE: the molar volume of any gas at STP is 22.4 L/mol

Question 32

Fill in the blank. ___________________ states that the pressure multiplied by the volume is equal to the number of moles multiplied by the universal gas constant and the temperature.

Answer 32

The Ideal Gas Law

P=nrt
V