Question

Please give an example of how each of the following gas laws affects a pilot who is in flight and explain the condition (altitude, etc.) the pilot is in when he or she experiences trouble due to each of the gas laws:

- Boyle's Gas Law (gas expansion)

- Dalton's Gas Law (partial pressures)

- Henry's Gas Law (decompression)

- Graham's Gas Law (gaseous diffusion)

Thank you!

Answer 1

Boyle's Gas Law (gas expansion)

It states that the volume of a gas is inversely proportional to the pressure on the gas as long as the temperature remains constant. A gas will expand when the pressure on it is decreased. This law holds true for all gases, even those trapped in body cavities. Altitude also plays an important role. For example a volume of gas at sea level pressure will expand to approximately twice its original volume at 18,000 feet, nearly nine times its original volume at 50,000 feet.

Dalton's Gas Law (partial pressures)

It states that the total pressure of any mixture of gases (with constant temperature and volume) is the sum of the individual pressures (also called partial pressure) of each gas in the mixture. Dalton's Law lets us calculate the partial pressure of the oxygen in the atmosphere at any altitude

Henry's Gas Law (decompression)

It states that the amount of gas dissolved in a solution is proportional to the partial pressure of the gas over the solution.

A bottle of carbonated liquid demonstrates Henry's Law. When the bottle is uncapped, the carbon dioxide (CO2) in the mixture will slowly diffuse to the atmosphere until the pressure of CO2 in the liquid equals the pressure of CO2 in the surrounding air. The soda will then be "flat." A bottle of soda opened in an unpressurized aircraft at 10,000 feet will foam and overflow. The opposite will happen with soda opened at pressures greater than one atmosphere. A champagne cork won't pop in a diving bathysphere pressurized for deep ocean exploration.

Graham's Gas Law (gaseous diffusion)

It states that a gas at higher pressure exerts a force toward a region of lower pressure. There's a permeable or semi-permeable membrane separating the gases, and gas will diffuse across the membrane from the higher pressure to the lower pressure. This will continue until the pressure of the gas is equal, or nearly equal, on both sides of the membrane. Graham's Law is true for all gases and each gas in a mixture behaves independently. It's possible to have two or more gases in a solution diffusing in opposite directions across the same membrane and, in fact, this is what happens to make oxygen transfer possible in the cells and tissues of the human body.