Principles of gas exchange

Question 1

What is a gas?

Answer 1

Collection of simple molecules moving randomly in a space

Question 2

How do gas molecules move?

Answer 2

Move rapidly in straight lines
until they collide with other molecules
then they bounce away in a new direction

Question 3

What is the pressure of a gas?

Answer 3

Force created by gas molecules colliding with a surface

Question 4

What are the factors affecting pressure of a gas?

Answer 4

Volume

Number of gas molecules

Temperature

Question 5

What is the volume of a gas?

Answer 5

The amount of space that the gas molecules occupy

Question 6

How does increased volume of a gas affect its pressure?

Answer 6

Gas molecules have more space to move around in
fewer collisions with surface
decreases pressure

Question 7

How does decreased volume of a gas affect its pressure?

Answer 7

Gas molecules have less space to move around in
more collisions with surface
increases pressure

Question 8

What is the overall relationship between volume of a gas and its pressure?

Answer 8

Inversely proportional

Question 9

How does an increased number of gas molecules affect its pressure?

Answer 9

More gas molecules moving around in the same amount of space
more collisions with surface
increases pressure

Question 10

How does a decreased number of gas molecules affect its pressure?

Answer 10

Fewer gas molecules moving around in the same amount of space
fewer collisions with surface
decreases pressure

Question 11

What is the overall relationship between number of gas molecules and its pressure?

Answer 11

Proportional

Question 12

How does increased temperature of a gas affect its pressure?

Answer 12

Gas molecules have more energy
move around faster
more and harder collisions with surface
increases pressure

Question 13

How does decreased temperature of a gas affect its pressure?

Answer 13

Gas molecules have less energy
move around slower
fewer and weaker collisions with surface
decreases pressure

Question 14

What is the overall relationship between temperature of a gas and its pressure?

Answer 14

Proportional

Question 15

What is the equation for the pressure of a gas?

Answer 15

Pressure = (n x T x R) / V

n = number of gas molecule
T = temperature
R = constant
V = volume of gas

Question 16

What is the partial pressure of a gas?

Answer 16

In a mixture of gases

the pressure that each gas exerts is its partial pressure

Question 17

What is the total pressure of a gas mixture?

Answer 17

In a gas mixture

the total pressure is the sum of all the partial pressures of the different gases in the mixture

Question 18

What is meant by atmospheric pressure?

Answer 18

Pressure exerted by the weight of the air

Question 19

How does atmospheric pressure change from higher altitudes to lower altitudes? Why?

Answer 19

It increases
because force of gravity increases
so the weight of air increases
more molecules in same volume

Question 20

What is the actual atmospheric pressure at sea level?

Answer 20

101kPa = 760mmHg = 1atm

Question 21

What gases make up atmospheric air? What are there relative proportions?

Answer 21

Nitrogen - 79%

Oxygen - 21%

Question 22

How are the partial pressures of gases in atmospheric air calculated?

Answer 22

Nitrogen = 79% x 101kPa

Oxygen = 21% x 101kPa

Question 23

What is the symbol for partial pressure?

Answer 23

p

Question 24

What do gas molecules do they come into contact with fluid?

Answer 24

Some gas molecules dissolve in the fluid

Question 25

What affects the partial pressure of a gas dissolved in a fluid?

Answer 25

The concentration of gas molecules dissolved in the fluid The solubility coefficient of the gas

Question 26

How does an increased concentration of gas molecules dissolved in a fluid affect the partial pressure of the gas in the fluid?

Answer 26

More gas molecules in same volume more collisions with surface higher partial pressure

Question 27

How does a decreased concentration of gas molecules dissolved in a fluid affect the partial ressure of the gas in the fluid?

Answer 27

Fewer gas molecules in same volume fewer collisions with surface lower partial pressure

Question 28

What is the overall relationship between concentration of gas molecules dissolved in a fluid and the partial pressure of the gas in the fluid?

Answer 28

Proportional

Question 29

What is meant by the solubility coefficient of a gas?

Answer 29

How well the gas dissolves in water

Question 30

How does a lower solubility coefficient of a gas affect the partial pressure of the gas dissolved in a fluid?

Answer 30

Gas doesn't dissolve as well in water, less surrounded by water molecules makes more collisions with surface increased partial pressure

Question 31

How does a higher solubility coefficient of a gas affect the partial pressure of the gas dissolved in a fluid?

Answer 31

Gas dissolves better in water, more surrounded by water molecules makes fewer collisions with surface decreased partial pressure

Question 32

What is the overall relationship between the solubility coefficient of a gas and the partial pressure of the gas dissolved in a fluid?

Answer 32

Inversely proportional

Question 33

What do water molecules do when they come into contact with air?

Answer 33

Water molecules evaporate from the fluid into the air as water vapour

Question 34

What is meant by vapour pressure of water?

Answer 34

Partial pressure of water vapour in air

Question 35

What are the factors of vapour pressure of water?

Answer 35

Temperature

Question 36

How does increased temperature affect vapour pressure of water?

Answer 36

Water molecules have more energy more of them evaporate from fluid into air as water vapour more water vapour in air higher vapour pressure

Question 37

How does decreased temperature affect vapour pressure of water?

Answer 37

Water molecules have less energy fewer evaporate from fluid into air as water vapur less water vapour in air lower vapour pressure

Question 38

What is the overall relationship between temperature and vapour pressure?

Answer 38

Proportional

Question 39

What direction do gases diffuse in?

Answer 39

From higher partial pressure to lower partial pressure | down their partial pressure gradient

Question 40

What are the factors affecting the rate of diffusion of a gas in a fluid?

Answer 40

Pressure difference Solubility of gas in fluid Cross-sectional area of fluid Diffusion distance Molecular weight of gas Temperature of fluid

Question 41

How does the pressure difference affect the rate of diffusion of a gas in a fluid?

Answer 41

Bigger partial pressure difference between the two areas | the faster the rate of diffusion

Question 42

What is the overall relationship between the pressure difference and the rate of diffusion of a gas in a fluid?

Answer 42

Proportional

Question 43

How does an increased cross-sectional area of fluid affect the rate of diffusion of a gas in a fluid?

Answer 43

More space for gas molecules to diffuse through more gas molecules diffuse across faster rate of diffusion

Question 44

How does a decreased cross-sectional area affect the rate of diffusion of a gas in a fluid?

Answer 44

Less space for gas molecules to diffuse through fewer gas molecules diffuse across reduced rate of diffusion

Question 45

What is the overall relationship between the cross-sectional area of the fluid and the rate of diffusion of a gas in a fluid?

Answer 45

Proportional

Question 46

How does increased diffusion distance affect the rate of diffusion of a gas in a fluid?

Answer 46

Takes longer for gas molecules to diffuse across that distance reduced rate of diffusion

Question 47

How does decreased diffusion distance affect the rate of diffusion of a gas in a fluid?

Answer 47

Doesn't take as much time for gas molecules to diffuse across faster rate of diffusion

Question 48

What is the overall relationship between the diffusion distance and the rate of diffusion of a gas in a fluid?

Answer 48

Inversely proportional

Question 49

How does increased solubility of a gas affect the rate of diffusion of a gas in a fluid?

Answer 49

More gas molecules dissolve into fluid more of them diffuse across increased rate of diffusion

Question 50

How does decreased solubility of a gas affect the rate of diffusion of a gas in a fluid?

Answer 50

Fewer gas molecules dissolve in fluid fewer of them diffuse across decreased rate of diffusion

Question 51

What is the overall relationship between the solubility of a gas and the rate of diffusion of a gas in a fluid?

Answer 51

Proportional

Question 52

How does increased molecular weight of a gas affect the rate of diffusion of a gas in a fluid?

Answer 52

Heavier gas molecules have less kinetic energy move slower reduced rate of diffusion

Question 53

How does decreased molecular weight of a gas affect the rate of diffusion of a gas in a fluid?

Answer 53

Lighter gas molecules have more kinetic energy move faster faster rate of diffusion

Question 54

What is the overall relationship between the molecular weight of a gas and the rate of diffusion of a gas in a fluid?

Answer 54

Inversely proportional

Question 55

Which of the factors of the rate of diffusion of a gas in a fluid are properties of the gas itself?

Answer 55

Solubility of gas Molecular weight of gas

Question 56

What are the factors of a diffusion coefficient of a gas?

Answer 56

Solubility of gas Molecular weight

Question 57

What is the diffusion coefficient of a gas?

Answer 57

Tells us the diffusion rate of a gas in a fluid at a certain partial pressure difference

Question 58

Does oxygen or carbon dioxide have a higher solubility coefficient?

Answer 58

Carbon dioxide

Question 59

Does oxygen or carbon dioxide have a larger molecular weight?

Answer 59

Carbon dioxide

Question 60

Does oxygen or carbon dioxide have a higher diffusion coefficient?

Answer 60

Carbon dioxide