Gas Laws and Gas Cylinders

Question 1

Daltons Law

Answer 1

total pressure of a gas is equal to the sum of the pressure of individual gases in a mixture

Question 2

ambient pressure

Answer 2

pressure of the surrounding (ex gas or liquid)

Question 3

Alveolar Gas Equation

Answer 3

PAO2 = FiO2 x (Pbarometric-PalveolarH2O) - PaCO2/RQ

Question 4

RQ

Answer 4

(=VCO2-VO2) .8 reflects 8 CO2 molecules produced for every 10 O2molecules burned. means more O2 leaves alveoli than is returned in the form of CO2 to alveoli.

Question 5

alveolar arterial oxygen gradient

Answer 5

(A-a)DO2

Question 6

arterial-alveolar ratio

Answer 6

PaO2/PAO2 ratio. better for high FiO2

can also be PaO2/FiO2. for this way, less than 200 means acute RDS. used to quantify hypoxemia

Question 7

reasons for (A-a)DO2 difference being normal

Answer 7

regional VA/Q mismatch (largest influence)

anatomic shunt of blood, like thespian circulation or bronchial circulation)

Question 8

pathological A-a O2 difference reasons

Answer 8

significant VA/Q mismatch
intrapulmonary shunts
Alveolar-cap membrane diffusion block
PFO

Question 9

henrys law

Answer 9

amount of gas dissolved in liquid is directly proportional to pressure applied to that gas as it overlies the liquid.
Concentration of gas = Pressure of gas/KH
(KH is a constant, solubility of gas in particular solvent. measures likelihood to leave liquid to gaseous state.)
(Pressure of gas is partial pressure of gas above liquid)

Question 10

Boyles Law

Answer 10

at a constant temperature, pressure of a gas is inversely proportional to volume. increased pressure in decreased volume. related to more collisions in a smaller container.
P1 x V1 = P2 x V2

Question 11

Charles Law

Answer 11

at a constant pressure, the volume of a gas is directly proportional to its absolute temperature. increased temperature (kelvins) = increased volume.
V1/T1=V2/T2

Question 12

Boyles and Chalres’ Law Combined

Answer 12

P1V1/T1 = P2V2/T2

Question 13

Gay-Lussacs Law

Answer 13

at a constant volume, pressure of a gas is directly proportional to absolute temp. increased temperature is increased pressure.
P1/T1=P2/T2

Question 14

Ideal Gas Law

Answer 14

PV=nRT or V=nRT/P

where R is a constant at 62.36L

Question 15

how to calculate R for ideal gas law

Answer 15

PV/nT=R where 760mmHgx22.4L/1mole x273k = 62.36L mmHg /mole K

Question 16

Joule Thompson Effect for Compression

Answer 16

endothermic reaction, warmer. KE of molecules increased when compressed and therefore can give off heat.
narrow valve can compress gas.

Question 17

Joule Thompson Effect for Expansion

Answer 17

exothermic reaction, cooler.

Question 18

Adiabatic Effect

Answer 18

a gas in a container which is isolated thermally from its environment becomes warmer when it is compressed and cooled when it expands. super rapid, thats why we feel it.