Review Label which units are pressure and which are volume: Atm ________cm^3 ________ L _________ torr _________

MS. HAAPALA The Gas Laws

Chemistry Standard 4: Gases and their Properties Standard 4. The kinetic molecular theory describes the motion of atoms and molecules and explains the properties of gases. c. Students know how to apply the gas laws to relations between the pressure, temperature, and volume of any amount of an ideal gas or any mixture of ideal gases.

Molecules of a Gas What happens to the gas molecules when you raise the temperature? What happens to the pressure if you decrease the volume? WHY?  30 second discussion with your neighbors When you raise the temperature the gas molecules move faster. When you decrease the volume the pressure goes up because there are more collisions in a smaller area. REMEMBER: Pressure = Force/Area

Bell Jar What happens when you breathe? How do your lungs work? What do you think will happen when I reduce the pressure in the bell jar? WHY? 400 Marshmallows in a Vacuum dmv-iPQvA dmv-iPQvA

Pressure and Volume: Boyle’s Law The absolute pressure and volume of a given mass of confined gas are inversely proportional if the temperature remains unchanged within a closed system. Pressure Simulation properties

Pressure and Volume – Boyle’s Gas Law _sim.html _sim.html

BOYLE’S LAW: P1V1=P2V2 When the pressure decreases the volume increases and vice versa (TEMPERATURE CONSTANT) Formula: P1V1 = P2V2  1 = initial (start)  2 = final (end) When one goes up the other goes down – inverse relationship (opposite affect)

Practice Problems If the pressure initially is at 100 Pa and the volume is 2 L, what is the new pressure if the volume is compressed to 1 L? Answer: 200 Pa What is the new pressure at 2 L if the initial pressure is 4 atm at 1 L? Answer: 2 atm