NAME______ideal-HW.doc

Ideal Gas Law 1. List known variables (with units). State what you are calculating. PV=nRT 2. Write the appropriate law. where P = pressure (kPa or atm) 3. Solve the Law for the desired V = Volume (liters) variable n = number of moles of gas 4. Plug the known variables (with T = Absolute Temperature (Kelvin) units) into the Solved Law. 5. Calculate the unknown variable 8.314liters kiloPascals 0.0821liters atmospheres 6. State the answer with units R  or R  moles  Kelvin moles  Kelvin

1. Use the ideal gas law to calculate the volume 11 moles CO2 at standard conditions?

List Variables: nRT LAW: PV = nRT V  P P = 100 kPa SOLVED FOR V plug in values T = 273º K nRT n = 11 moles of CO2 V  (11)(8.314)(273) R = 8.314 V  P (100)

V= 250 liters

Standard Conditions vary a bit. Here 100 kPa was used as standard pressure.

2. Calculate the volume of 1 mole CO2 of at standard conditions?

List Variables:

A value of 22.4 liters would be P = 100 kPa obtained using Avogadro’s T = 273º K plug in values Principle. These values are close enough to be considered to agree. n = 1 mole of CO2 (1)(8.314)(273) R = 8.314 V  (100) LAW: PV = nRT V= 22.6 liters SOLVED FOR V

Volume = 22.6 liters 3. Average lung capacity for a person is 4 liters. At 37˚C (body temperature) and 110kPa, how many moles of Oxygen gas can you lungs hold?

List Variables: LAW: PV = nRT Plug in values

SOLVED FOR n V = 4 liters (110)(4)

P = 110 kPa n  PV (8.314)(310) T = 37ºC +273 = 310º K n  RT n = ? R = 8.314 n = .171 moles of Oxygen

# of moles in your lungs = .171 moles

4. 40 grams of methane are held in a container with a volume of 2.5 liters. The methane is at 200˚ C. What is the pressure in kPa? nRT P  Calculate Molar Mass of CH4 List Variables: V

C – 1 × 12 g/mol = 12 g/mol plug in values V = 2.5 liters H – 4 × 1 g/mol = 4 g/mol T = 200 + 273= 473º K (2.5)(8.314)(473) P  n = 2.5 moles of CH4 (2.5) 16 g/mol R = 8.314

P= 3932 kPa

LAW: PV = nRT

Calculate # of Moles of CH2 SOLVED FOR P

40g mole   2.5 moles CH nRT 4 1 16g P  V Pressure = 3932 kPa

5. To what temperature must 7 moles of He be heated to create a pressure of 1.2 atmospheres in a 2500 liter container? Plug in values List Variables: LAW: PV = nRT

SOLVED FOR T (1.2)(2500) V = 2500 liters T  T = ? PV (7)(.0821) P = 1.2 atm T  n = 7 moles of He nR T = 5220 ºK R = .0821

Temperature = 5220 ºK