Gas laws

Question 1

Define total pressure

Answer 1

the total sum of all the collision forces

Question 2

Define Charles’s law

Answer 2

For a fixed mass of gas at a constant pressure, the volume is directly proportional to the temperature

Question 3

Name the four gas laws

Answer 3

-Charles’s law
-Boyles’s law
-Henry’s law
-Dalton’s law

Question 4

Why is Charles’s law important?

Answer 4

Important in lung function testing as air cools as it is expired

Question 5

Define Boyle’s law

Answer 5

For a fixed mass of gas the product of volume and pressure are always the same providing the temperature is constant.

Question 6

What’s the equation for Boyle’s law?

Answer 6

P x V = constant

Question 7

Using Boyle’s law what happens to volume when pressure increases?

Answer 7

volume decreases

Question 8

Equation for Boyle’s law

Answer 8

P1 V1 = P2 V2

Question 9

Using Boyle’s law what happens when you decrease volume?

Answer 9

-collisions increase
-presure increases

Question 10

Draw the graph fo Charles’s law

Answer 10

straight line

Question 11

Draw the graph for Boyles law

Answer 11

inversly proportional curve, look at powerpoint

Question 12

Define atmospheric pressure

Answer 12

the constant movement and collision of gas particles exerts pressure

Question 13

What is pressure exerted by air known as?

Answer 13

barometris pressure

Question 14

what is barometric pressure measured in?

Answer 14

kilopascals (KPa)
or
mmHg

Question 15

what is barometric pressure at sea level?

Answer 15

101KPa

Question 16

What is 1KPa equal to in mmHg?

Answer 16

7.5mmHg

Question 17

What is 1mmHg equal to in Kpa?

Answer 17

0.133

Question 18

Example- if the barometric pressure is 760mmHg what is the Kpa?

Answer 18

760 x 0.133 = 101.1 KPa

Question 19

List the percentage of gases in the air

Answer 19

Nitrogen-78%
oxygen-20.8%
Argon-0.9%
Carbon dioxide-0.04%
other gases- 0.17%

Question 20

Define Dalton’s law of partial pressure

Answer 20

the total pressure of a mixture of gases is equal to the sum of the partial pressure that each gas would exert in isolation.

e.g 5KPa + 15Kpa = 20 KPa

Question 21

what is the equation for partial pressure?

Answer 21

% of gas x atmospheric pressure

Question 22

example- partial pressure of oxygen- 20.9%

Answer 22

20.9% x 101kpa
0.209 x 101KPa
=21.1 KPa

Question 23

at sea level the atmospheric pressure is 101KPa which is?

Answer 23

this is the sum of partial pressures of constitueant gases

Question 24

What are three factors that affect the movement of gases?

Answer 24

-pressure gradient
-solubility of gas in liquid
-temperature

Question 25

define diffusion

Answer 25

the movement of a substance from an area of higher concentration to an area of lower concentration

Question 26

The greater the partial pressure difference between the two areas….

Answer 26

more rapidly the gas moves

Question 27

Define Henry’s gas law

Answer 27

-gases dissolved in liquid

-the number of molecules dissolving in liquid is directly proportional to the partial pressure at the surface of the gas

Question 28

What is the equation for Henry’s law and what does each part mean?

Answer 28

P = kH.C
p-partial pressure of the gas in the atmosphere above the liquid
C- concentration of dissolved gas
KH-Henry’s law constant of gas-depends on the solute, solvent and temperature

Question 29

Give an example of what happens during Henry’s law

Answer 29

-intital state-no O2 in solution
-O2 dissolves
-at equilibrium PO2 in air and water is equal. Low O2 solubility means concerntations are not equal

Question 30

What happens to pressure at high altitudes?

Answer 30

decreases

Question 31

What happens to the partial pressure of oxygen at a high altitude?

Answer 31

decreases

Question 32

What is the KPa of oxygen at high altitudes of 33Kpa?

Answer 32

20.9% x 33 = 6.90KPa

Question 33

Define water vapour pressure

Answer 33

the pressure exerted by molecules of water vapour in gaseous form

Question 34

what is the water pressure vapour standard number?

Answer 34

PH20= 6.3KPa at 37 degrees body temp

Question 35

what is the partial pressure of moist inspired oxygen?

Answer 35

PIO2 =20.9% x (PB - saturated water vapour pressure at 37 degrees

pio2 = 0.209 x (101- 6.3)
=0.29 x 94.7
=19.8

Question 36

what are lung volumes measurements standardised and reported at?

Answer 36

body temperature and pressure saturated with water (BTPS)