The Ideal Gas Law

Ideal GasReal Gas Made of small particles that have mass Same Mostly Empty SpaceSame Low densitySame Particles are in constant motion Same No attractive or repulsive forces between particles Small attractive or repulsive forces between particles Particles have no volumeParticles have small volume Collision are elastic (lose no KE) Collision are NOT elastic (lose KE)

P 1 x V 1 = P 2 x V 2 = R n 1 x T 1 n 1 x T 2

Standard Temperature and Pressure

The conditions 0 0 C and 1 atm are called standard temperature and pressure (STP). PV = nRT R = PV nT = (1 atm)(22.414L) (1 mol)( K) R = L atm / (mol K) Experiments show that at STP, 1 mole of an ideal gas occupies L.

What is the volume (in liters) occupied by 49.8 g of HCl at STP? PV = nRT V = nRT P T = 0 0 C = K P = 1 atm n = 49.8 g x 1 mol HCl g HCl = 1.37 mol V = 1 atm 1.37 mol x x K Latm molK V = 30.6 L

GIVEN: P = ? atm n = mol T = 16°C = 289 K V = 3.25 L R = L  atm/mol  K WORK: PV = nRT P(3.25)=(0.412)(0.0821)(289) L mol L  atm/mol  K K P = 3.01 atm Calculate the pressure in atmospheres of mol of He at 16°C & occupying 3.25 L.

GIVEN: V = ?V = ? n = 85 g T = 25°C = 298 K P = kPa R = dm 3  kPa/mol  K Find the volume of 85 g of O 2 at 25°C and kPa. = 2.7 mol WORK: 85 g 1 mol = 2.7 mol g PV = nRT (104.5)V=(2.7) (8.315) (298) kPa mol dm 3  kPa/mol  K K V = 64 dm 3

Example A gas sample occupies a volume of L at 38°C and atm. What will be the temperature of the sample if it occupies L at 1.25 atm?

Example A sample of nitrogen gas in a 2.00 L container has a pressure of mmHg at 25°C. What would be the pressure on the sample in a 1.00 L container at 125°C?

Example The gas pressure in an aerosol can is 1.5 atm at 25 o C. Assuming that the gas inside obeys the ideal-gas equation, what would the pressure be if the can were heated to 450 o C?

What volume does 48.0 g of methane, CH 4, occupy at 140. o C under a pressure of 1280 torr?

A 250. mL flask contains a mixture of nitrogen, oxygen, and helium at a temperature of 27 o C and a pressure of atm. How many moles of gas are present?

What pressure in kilopascals is exerted by g of carbon dioxide in a 1.00 L flask at 100 o C?

What is the volume of a 15.0-g sample of neon gas at kPa and 39°C?

At what temperature will 2.85 moles of hydrogen gas occupy a volume of 0.58 L at 1.00 atm?