Chapter 7,Lesson 3: The Behavior of Gases

EQ: How are the forces between particles different in solids, liquids, and gases?

October 16, 2012

ISN page 53

Kinetic Molecular Theory

Matter made of small particlesParticles in constant random motionParticles collide with each other and their

containerEnergy not lost in the collisions

Gases behave different than solids and liquids.Affected by changes in

TemperaturePressureVolume

Pressure

Force per unit areaInverse relationship between pressure

and volume at constant temperatureLower volume = higher pressure and vice versa

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Boyle’s Law

At a constant temperature: V2=P1V1/P2

Example: What is the final volume of a gas if the initial volume was 500 mL and the pressure increased from 200 kPa to 400 kPa V2=200 kPa x 500 mL/400 kPa

V2=100000/400=250 mL

Boyle’s Law, cont.

Real life: airplane ear pain = lower air pressure at altitude and the volume in your inner ear tries to increase. Ouch!

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Temperature and gases

Low temperature = low volumeIncreases to temp increases in volume

Charles’s Law: volume of gas increases as temp increases if pressure is constantV1/T1 = V2/T2

Charles’s Law, cont.

Example: A sample of helium gas has a volume of 50 mL at 300 degrees K. At what temperature would the gas have a volume of 70 mL?V1/T1=V2/T2

50 mL/300 K = 70 mL/T2

(300 K x 70 mL)/50 mL = 420 K

ISN page 52

Design a concept bookmark or t-shirt, front and back, one side showing Charles’s Law and the other showing Boyle’s Law.

Include a paragraph describing each side of the bookmark or t-shirt.

Remember to use COLOR!

Figure 18!!!

Thoughts to ponder:1. What is the slope of the line?2. What is the reason for multiple lines?3. What do the dashed lines represent?