1. Chapter 12 Sections 1and 2 Gas- matter that has no definite shape or volume, takes both the shape and volume of its container Kinetic Theory of Gases Basic Assumptions of Kinetic Theory: 1)no attractive or repulsive forces exist between gas particles -particles are very far apart from one another -empty space between particles explains gas compressibility

2. 2)gas particles move in constant random motion 3)all collisions between gas particles are perfectly elastic -during collisions kinetic energy is transferred without loss from one particle to another -kinetic energy remains constant

3. Variables Affecting Gases 1)Pressure (P) -measured in kPa, mm Hg, atm **101.3 kPa = 760 mm Hg = 1 atm

4. Convert: A)3.45atm → mm Hg and kPa (3.45atm/1) x (760mmHg/1atm)= 2622.00mmHg (3.45atm/1) x (101.3kPa/1atm)= 349.49kPa B) 893 mm Hg → kPa and atm (893mmHg/1) x (101.3kPa/760mmHg) = 119.03kPa (893mmHg/1) x (1atm/760mmHg) = 1.18atm

5. 2)Volume (V) -amount of space an object occupies -expressed in Liters (L) 3)Temperature (T) -how hot or cold something is -must be expressed in K *remember °C + 273= Kelvin 4) Amount of Gas (n) -expressed in moles

6. **Remember STP (standard temp and pressure) T= 273 K, 0°C P= 101.3 kPa, 760 mm Hg, 1 atm

7. Effects on Pressure 1)Amount of Gas -more gas particles = more collisions = more pressure Ex- pumping a tire with air 2)Volume -increase in volume = decrease in pressure -the more the gas is compressed the greater the pressure Ex- pistons in car engines

8. 3)Temperature -KE increases as temp increases causing more collisions and greater pressure Ex- helium balloons in cold weather