Kinetic= motion All matter consists of small particles The molecules are in constant, random, rapid motion All collisions are elastic (no net loss of energy)
As temperature increases, the molecules velocity increases, increasing the pressure on the container.
The average distance traveled between collisions. An oxygen molecules will collide with other molecules 4.5 billion times per second!
The temperature of a substance is a measure of the average kinetic energy of its particles. Absolute zero – the temperature at which molecular motion stops ( o C)
Caused by gas molecules colliding with the sides of a container Force per unit area Units: 1 atm = kPa = 760 mmHg = 760 torr
How many mmHg is in one kPa? 7.5 mmHg
Open Manometer – atmosphere exerts pressure on one side and gas sample exerts pressure on the other side ◦ Add if gas pressure is greater ◦ Subtract if air pressure is greater Closed Manometer (barometer) – vacuum on one side, gas pressure on the other side ◦ No addition or subtraction necessary
StateShapeVolumeCompressible?Flows?SolidDefiniteIndefiniteNoNo LiquidIndefiniteDefiniteNoYes GasIndefiniteDefiniteYesYes
The pressure produced when vapor particles above a liquid collide with container walls; a dynamic equilibrium exists between the liquid and the vapor. Vapor pressure increases with temperature. A substance with weak intermolecular forces has a high vapor pressure and low boiling points. (these are volatile – alcohols, ethers) A substance with strong intermolecular forces has a low vapor pressure and high boiling point (these are nonvolatile – water, molasses, glycerol)
Critical Point – above this temperature, no amount of pressure can liquefy it. Triple Point – all three phases are in equilibrium