1. Chapter 11B Combined & Ideal Gas Law Problems
West Valley High School
General Chemistry
Mr. Mata

2. COMBINED GAS LAW PROBLEM #1
A Helium balloon has a volume of 3.0 L at 1 atm and 273 K. Calculate its volume at 2 atm and 27oC.
V1 = 3 L V2 = ?
P1 = 1 atm
T1 = 273 K
P2 = 2 atm
T2 = = 300K

3. SUBSTITUTE AND SOLVE T1 T2 V2 = P1V1T2 T1P2 V2 = (1 atm)(3 L)(300 K)
P1V1 = P2V2
T T2
V2 = P1V1T2
T1P2
V2 = (1 atm)(3 L)(300 K)
(273 K )(2 atm)
V2 = 1.7 L

4. COMBINED GAS LAW PROBLEM #2
A hydrogen balloon has a temperature of 320 K and a volume of 7.5 L and 3 atm of pressure. Calculate its pressure at 58 C and 10.5 L.
V1 = 7.5 L V2 = 10.5 L
P1 = 3 atm
T1 = 320 K
P2 = ?
T2 = = 331 K

5. SUBSTITUTE AND SOLVE T1 T2 P2 = P1V1T2 T1V2 P2 = (3 atm)(7.5 L)(331 K)
P1V1 = P2V2
T T2
P2 = P1V1T2
T1V2
P2 = (3 atm)(7.5 L)(331 K)
(320 K )(10.5 L)
P2 = 2.2 atm

6. Ideal Gas Law Problem #1
Calculate the temp of 7.5 g H2 gas if the volume is 52.5 L and pressure is 0.8 atm.
First convert values to proper units:
n = 7.5 g H2 x 1 mol H2 = 3.8 mol H2
2 g H2
T = ? V = 52.5 L
P = 0.8 atm R = L atm / mol K

7. Substitute and Solve PV = nRT T = PV nR T= (0.8 atm)(52.5 L)
(3.8 mol)(.0821 L atm/ mol K)
T= K

8. Ideal Gas Law Problem #2
Calculate the pressure of 60 g NH3 gas if the volume is 40 L and temp is 72 C.
First convert values to proper units:
n = 60 g NH3 x 1 mol NH3 = 3.5 mol NH3
17 g NH3
T = 72 C = 345 K V = 40 L
P = ? R = L atm / mol K

9. Substitute and Solve PV =nRT P = nRT V
P= (3.5 mol)(.0821 L atm/ mol K)(345 K)
(40 L)
P= 2.5 atm

10. Chapter 11 SUTW Prompt
Describe how pressure, temperature, and volume are related in the combined gas law.
Complete a sentence paragraph using the SUTW paragraph format. Hilight using green, yellow, and pink.
Due Date: Tuesday, January 17th, 2017(start of class).