Chapter 19

The Ideal Gas Equation

The Ideal Gas Equation

• P = pressure

• V = volume

• n = number of moles

• T = temperature

• R = gas constant

PV = nRT

R values

a

I

A

How many moles of gas will a 1250 cm3 flask hold at 35.0C and a pressure of 95.4 kPa?

0.0466 mol

What pressure in kPa is exerted by 0.00306mol of gas in a 25.9cm3 container at 9.0°C?

277 kPa

The Concorde, a supersonic passenger jet flew its last flight on November 26, 2003. It was a major pollution concern in that it produced 6.6 x 104 kg of CO2 for each hour of flight at

42 kPa and 627°C. How many liters of CO2 is this?

The Concorde, a supersonic passenger jet flew its last flight on November 26, 2003. It was a major pollution concern in that it produced 6.6 x 104 kg of CO2 for each hour of flight at

42 kPa and 627°C. How many liters of CO2 is this?

2.67 x 108 L = 267,000,000 L

Gram Formula Mass (Molar Mass)

• The ratio of grams per mole.

H2 = 2 g/mol

CO2 = 44 g/mol

H2O = 18 g/mol

• We can therefore calculate gram formula mass if we know the grams and the moles.

• GFM = grams/moles

A poisonous gas is leaking out of an old gold mine. A chemist collects 4.564 grams of the gas and uses the ideal

gas equation to determine that this is 0.163 moles. Is the gas CH4, CO, or AsH3

MM = 28 g/mol

Remember our first question today.

How many moles of gas will a 1250 cm3 flask hold at 35.0C and a pressure of 95.4 kPa?

n = PV / RT = 0.0466 mol

• 0.186 g of a gas at 35.0C and 95.4 kPa occupies a volume of 1250 cm3. Is the gas H2, He, O2, or CO2?

GFM = grams/mole

= 0.186 g/0.0466 moles

= 3.99 g/mol ≈ 4 g/mol

Therefore the gas is most likely He.

1.00g of a gas occupies 0.820 dm3 at 760 torr and 3.0°C. The gas is most likely:

(a) BH3 (b) B4H10 (c) B2H6 (d) B3H12 (e) B5H14

Homework

• Worksheet: The Ideal Gas Equation