Chapter 14 Gas Laws Kinetic Molecular Theory – Assumes gas particles are small particles w/lots of space between them – No attractive forces; particles free to move & take shape of container – Move rapidly in random, straight lines w/elastic collisions; KE proportional to T (in K) Four variables to describe a gas: P (kPa), V (L),T (K), & n (moles)

1. n – moles of gas – Affect Pressure – amount of gas in moles (n) -  # particles,  # collisions,  P – n & P are directly proportional 2. V- volume of gas – Affect Pressure – volume in L, –  volume,  collisions,  P; – V & P are inversely proportional 3. T- temperature of gas – Affect Pressure – Temp in K –  T,  KE, move faster,  collisions,  P – T & P are directly proportional 4. P – pressure of gas – in kPa 4 Variables Used to Explain Gases

Boyles Law Practice P & V vary inversely P 1 V 1 =P 2 V 2 ;T & n constant Balloon w/ 30.0L of gas at 103 kPa. What volume will it have when P changes to 25.0 kPa? 1.00 L of a gas at standard temperature and pressure is compressed to 473 mL. What is the new pressure of the gas?

Boyles Law Practice In a thermonuclear device, the pressure of liters of gas within the bomb casing reaches 2.4 x 10 4 atm. When the bomb casing is destroyed by the explosion, the gas is released into the atmosphere where it reaches a pressure of 1.15 atm. What is the volume of the gas after the explosion?

Charles Law- V & T vary directly V 1 = V 2 T 1 T 2 – P & n constant; T in K Balloon is inflated at 24 º C w/a volume of 4.00L. When the balloon is heated to 58 º C, what is the new volume? Charles Law Practice

The temperature inside my refrigerator is about 270. Kelvin. If I place a balloon in my fridge that initially has a temperature of 296 Kelvin and a volume of 1.26 liters, what will be the volume of the balloon when it is fully cooled by my refrigerator?

Charles Law Practice A man heats a balloon in the oven. If the balloon initially has a volume of liters and a temperature of C, what will the volume of the balloon be after he heats it to a temperature of C? On hot days, you may have noticed that potato chip bags seem to “inflate”, even though they have not been opened. If I have a 125 mL bag at a temperature of 5 0 C, and I leave it in my car which has a temperature of C, what will the new volume of the bag be?

GayLussac’s Law- P & T (in K) vary directly – Constant V & n P 1 = P 2 T 1 T 2 A gas has a P of 103 kPa at 25 C. What is the P at 928 º C? Gay-Lussac’s Law Practice

Avogadro’s Law If 6.34 g of NO 2 gas has a volume of 18.7L at a certain temperature and pressure, what is the volume of 12.6g of NO 2 have at the same conditions?

Combined Gas Law Practice Combined Gas Law - Combines 3 other equations P 1 V 1 = P 2 V 2 T 1 T 2 A balloon is filled with 30.0L at 40.0 º C & 153 kPa. What volume will it have at STP? – Remember: (STP= 0 o C & kPa)

PV=nRT – P- pressure – V- volume – n- number of moles – R- constant match w/ P & V 8.31 L kPa / K mol – T- in K Ideal Gas Law

Cylinder w/ a volume of 20.0L with a P of 2.00X10 4 kPa at 28.0 º C. How many moles is this? 2.24 X 10 6 L CH 4 at a P of 1.50X 10 3 kPa at 42.0 ºC, how many kg of CH 4 ? Ideal Gas Law based on Kelvin for Temp.

Dalton’s Law- in a gas mixture, the partial pressures of gases added together makes the total pressure P T = P 1 + P 2 + P 3... Air contains oxygen, nitrogen, carbon dioxide and other gases. Find the P of oxygen if the total P is kPa, the pressure of nitrogen is kPa, the pressure of carbon dioxide is kPa and the pressure of the other gases is.940 kPa.

Diffusion- molecules move from [  ] to [  ] Effusion- gas escapes through a tiny hole Graham’s Law of Effusion- – rate of effusion inversely proportional to the square root of the gas’ molar mass – Lighter gases move faster One balloon with H 2 & one with He. Which one will effuse faster?