V. Combined and Ideal Gas Law

**Standard T and P (STP) Recall that STP is 1 atm and 0oC 0oC = 273 K 1 mole = 22.4 L @ STP

STP Problem #1 How many liters will 3.33 moles of Neon gas occupy at STP?

STP Problem #2 How many moles of fluorine gas will be contained in a 1.30 liter flask at STP?

A. The Combined Gas Law Pressure units must be the same Volume units must be the same Temperature must be in Kelvin

A. The Combined Gas Law Boyle’s Law (temperature remains constant )

A. The Combined Gas Law Gay-Lussac’s Law (volume remains constant )

A. The Combined Gas Law Charles’ Law (pressure remains constant )

Combined Gas Law Problem #1 The volume of a gas-filled balloon is 30.0 L at 40oC and 3 atm. What would the volume be if the balloon was reduced to STP?

Combined Gas Law Problem #2 A 5.00 L air sample has a pressure of 107 kPa at a temperature of -50.0˚C. If the temperature is raised to 102˚C and the volume expands to 7.00 L, what will the new pressure be?

B. Ideal Gases Ideal gases are imaginary gases that perfectly fit all of the assumptions of the kinetic molecular theory Gases consist of tiny particles that are far apart relative to their size All collisions (between particles and the walls) are elastic collisions (no energy lost)

B. Ideal Gases Cont. Gas particles are in constant random motion No forces of attraction between gas particles Average kinetic energy depends on temperature

C. Real Gases Real gases DO experience attractions between particles Real gases DO have volume Real gases DO NOT have elastic collisions

PV = nRT D. The Ideal Gas Law = 8.314 L∙ kPa mol ∙K P = pressure V = volume (in liters) n = number of moles R = Ideal Gas constant = 8.314 L∙ kPa mol ∙K = 0.0821 L∙ atm mol ∙K T = temperature (in Kelvin) **If there are moles or mass in your gas law problem, use the IDEAL GAS LAW**

R = 8.314 L∙ kPa mol ∙K R = 0.0821 L∙ atm mol ∙K Ideal Gas Law Problem #1 Calculate the number of moles of gas contained in a 3.0 L vessel at 300 K and a pressure of 152 kPa.

R = 8.314 L∙ kPa mol ∙K R = 0.0821 L∙ atm mol ∙K Ideal Gas Law Problem #2 What pressure in atmospheres (atm) will 297.6 g of methane (CH4) exert when it is compressed in a 12.00 L tank at a temperature of 45°C?