1. The Gas Laws

2. Units- are used to identify each variable Volume- mL, L, cm 3 Temperature- if given in °C convert to Kelvin- K Pressure- atm, torr, mmHg, psi (lbs/in 2 ), kPa

3. Boyle’s Law Pressure –Volume relationship For a given mass of gas, at constant temperature, the volume of the gas varies inversely with pressure. IF PRESSURE INCREASES  VOLUME___________ IF PRESSURE DECREASES  VOLUME___________ Equation: P 1 x V 1 = P 2 x V 2 Subscript 1 represents starting conditions. Subscript 2 represents final conditions. P= Pressure V= Volume Temperature is NOT included because it remains constant Why would the temperature have to remain constant?

4. Boyle’s Law Example A gas with a volume of 4L at a pressure of 90 kPa is allowed to expand until the pressure drops to 20 kPa. What is the new volume? Step 1: Determine values P1=V1=P2=V2=P1=V1=P2=V2= Step 2: Plug into equation Step 3: Solve for unknown Step 4: Check work

5. Charles’ Law Volume- temperature relationship For a given mass of gas, the volume of the gas is directly proportional to its Kelvin temperature if pressure is held constant. Temperature is always in Kelvin. 10 °C + 273= 283 K 25 °C + 273= 298K Equation: V 1 = V 2 T 1 T 2

6. Charles’ Law Example A balloon at 27 °C has a volume of 4.0 L. The balloon is heated to 57 °C. What is the new volume? Step 1: Determine values V1=T1=V2=T2=V1=T1=V2=T2= Step 2: Plug into equation Step 3: Solve for unknown Step 4: Check work

7. Gay-Lussac’s Law Pressure –Temperature relationship For a given mass of gas, the pressure is directly proportional to its Kelvin temperature if volume is held constant. Equation: P 1 = P 2 T 1 T 2 http://www.marymount.k12.ny.us/marynet/06stwbwrk/06gas/1amcslussac/amcsgaylussac.html

8. Gay-Lussac’s Example Step 1: Determine values P1=T1=P2=T2=P1=T1=P2=T2= Step 2: Plug into equation Step 3: Solve for unknown Step 4: Check work A sample of gas in a rigid container at 10 °C is at a pressure of 800 torr. What temperature will be necessary to change the pressure to 1100 torr?