5.2 Partial Pressure/Air

In atmospheric Air, what is it composed of? (4)

nitrogen, oxygen, argon, Carbon dioxide

Air: What % N2?

78%

Air: What % O2?

21%

Air: What % Ar?

0.93%

Air: What % CO2?

0.04%

Nitrogen fixing bacteria (base of food web), gives us _____ nitrogen.

useable (not gaseous)

Gasses move according to ?

pressure

The partial pressure equation is?

P_x = Ptotal x % Gas (in mix)

Pressure travels from high to?

low

To find out the partial pressure of N2 in a container with 600 mmHg and 50% N2 composition, write the equation & answer:

P_N2 = 600 mmHg x 0.50 = 300 mmHg

At equilibrium, if you have two chambers that are connected by a valve, the gas will be ____ on both sides.

even

If you have a gas mix w/ 70% Hydrogen and 30% helium, and the total pressure is 500 mmHg, what is the partial pressure of helium?

(500 × 0.3 =) 150 mmHg

Atmospheric Pressure is?

760 mmHg

When you have a gas at a certain partial pressure outside of the solution, what will it tend to do? (2)

dissolve into solution until reached equilibirum

Once equilibrium is reached, the partial pressure of the gas INSIDE the solution will _____ the partial pressure of the gas OUTSIDE

match

Ex. there’s a P_O2 of O2 at 100 mmHg out of solution, eventually, O2 is entering the solution at the same rate it’s leaving. So, the P_O2 in the solution is?

100 mmHg ^{(since it’s at equilibrium)}

If you increase a Partial Pressure of a gas outside of the solution, once at equilibrium, the gas in solution will ____ partial pressure as the increased outside.

match

Is the partial pressure in the solution actually exerting let’s say 100 mmHg of pressure?

no

The partial pressure within the solution just shows the:

tendancy of the gas to leave the solution ^{(dictates driving force to move out solution to reach equilibrium)}

Does O2 dissolve well in water?

no

Does CO2 dissolve well in water?

yes

So CO2 likes to stay in the water, and when it does, ___ tends to leave the water quickly.

O2

So let’s say these are outside: Pco2 = 100; Po2 = 100, but when you look in the solution, there are MORE CO2 molecules than O2. Does that mean the Partial Pressure of Oxygen will be less than Co2? If not, why?

no; partial pressure doesn’t say anything about concentration