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

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 = 27 +273 = 300K

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

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 = 58 +273 = 331 K

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

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 = 0.0821 L atm / mol K

Substitute and Solve PV = nRT T = PV nR T= (0.8 atm)(52.5 L) (3.8 mol)(.0821 L atm/ mol K) T= 134.6 K

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 + 273 = 345 K V = 40 L P = ? R = 0.0821 L atm / mol K

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

Chapter 11 SUTW Prompt Describe how pressure, temperature, and volume are related in the combined gas law. Complete a 8 - 10 sentence paragraph using the SUTW paragraph format. Hilight using green, yellow, and pink. Due Date: Tuesday, January 17th, 2017(start of class).