GASES

Importance of Gases Airbags fill with N 2 gas in an accident. Airbags fill with N 2 gas in an accident. Gas is generated by the decomposition of sodium azide, NaN 3. Gas is generated by the decomposition of sodium azide, NaN 3. 2 NaN 3 ---> 2 Na + 3 N 2 2 NaN 3 ---> 2 Na + 3 N 2

THREE STATES OF MATTER

General Properties of Gases There is a lot of “free” space in a gas. There is a lot of “free” space in a gas. Gases can be expanded infinitely. Gases can be expanded infinitely. Gases fill containers uniformly and completely. Gases fill containers uniformly and completely. Gases diffuse and mix rapidly. Gases diffuse and mix rapidly.

Properties of Gases Gas properties can be modeled using math. Model depends on— V = volume of the gas (L) V = volume of the gas (L) T = temperature (K) T = temperature (K) – ALL temperatures MUST be in Kelvin!!! No Exceptions! – K = C n = amount (moles) n = amount (moles) P = pressure (atmospheres) P = pressure (atmospheres)

Boyle’s Law P α 1/V This means Pressure and Volume are INVERSELY PROPORTIONAL (mass and Temp are constant) P 1 V 1 = P 2 V 2 As P goes up, V goes down. As P goes down, V goes up Robert Boyle ( ). Son of Earl of Cork, Ireland.

Boyle’s Law and Kinetic Molecular Theory 12/airplane/boyle.html 12/airplane/boyle.html

Boyle’s Law A bicycle pump is a good example of Boyle’s law. As the volume of the air trapped in the pump is reduced, its pressure goes up, and air is forced into the tire.

Charles’s Law If n and P are constant, then V α T V and T are directly proportional. V 1 V 2 = T 1 T 2 If temperature goes up, the volume goes up! If temperature goes up, the volume goes up! Jacques Charles ( ). Isolated boron and studied gases. Balloonist.

Charles’s original balloon Modern long-distance balloon

Charles’s Law 12/airplane/glussac.html 12/airplane/glussac.html

Gay-Lussac’s Law If n and V are constant, then P α T P and T are directly proportional. P 1 P 2 = T 1 T 2 If temperature goes up, the pressure goes up! If temperature goes up, the pressure goes up! Joseph Louis Gay- Lussac ( ) He was a ballonist.

Combined Gas Law The good news is that you don’t have to remember all three gas laws! Since they are all related to each other, we can combine them into a single equation. BE SURE YOU KNOW THIS EQUATION! P 1 V 1 P 2 V 2 = T 1 T 2

Combined Gas Law If you should only need one of the other gas laws, you can cover up the item that is constant and you will get that gas law! P1P1 V1V1 T1T1 P2P2 V2V2 T2T2 Boyle’s Law Charles’ Law Gay-Lussac’s Law =