2 MATTER Affected by temperature and pressure A change in temperature and/or pressure can change the state of matter of a substance
3 Kinetic Theory – Energy in Motion Three assumptions of how particles in matter behave 1. All matter is made of small particles - atoms, molecules and ions 2. These particles are in constant motion. The motion has no pattern. 3. These particles are colliding or crashing into each other and into the walls of their container.
4 Thermal EnergyThermal energy is the total energy of the particles in a material.Thermal energy includes kinetic energy and potential energySolid particles do not appear to be moving but they are! Solid particles move slowly.
5 Absorb or Release Thermal Energy When particles absorb thermal energy thenTemperature increases orTemperature remains constant and particles transition to more energetic phase of matterWhen particles release thermal energy thenTemperature decreases orTemperature remains constant and particles transition to less energetic phase of matter
6 TemperatureMeasure of the average kinetic energy of the vibrating or moving atoms or molecules of a substanceAbsolute zero = no movementHeat= the total kinetic energy of a substance
7 PressureThe force per unit area applied on a surface in a perpendicular directionThese gas molecules are constantly moving in random directions. When a molecule hits the container wall (green), it exerts a tiny force on the wall. The sum of these tiny forces, divided by the interior surface area of the container, is the pressure.
8 One atmosphere is defined as the pressure caused by the weight of all the overlying air at sea level or 14.7 pounds per square inch (psi).
9 Solid Low Temperature and/or High Pressure Low Kinetic energy Low Temperature and/or High PressureLow Kinetic energyDefinite pattern resulting in definite volume and definite shapeCan be an atom, ion or moleculeUsually in crystalline form, although some are glass
11 Liquid Less Pressure, More Kinetic Energy Less Pressure, More Kinetic EnergyDefinite volume, no definite shapeMelting point= the vibrations of the particles cause the forces holding the solid together to breakThese forces are called chemical bonds
12 BondsSolid water has MORE H-bonds (4) than liquid water (~2 )
14 If solids are more compact and more dense due to high pressure, why does solid water float? Most substances contract when temperaturesdecrease because the particles move closer together, but not water!
15 Why is solid ice less dense than liquid water? Water expands when it freezes into ice because water is a polar molecule.The negative and positive charges are attracted to one another so when they line up that leaves empty space. Therefore water expands when it freezes or changes from a liquid to a solid.
16 Gas Least pressure, most kinetic energy Least pressure, most kinetic energyNo definite shape, no definite volumeEvaporation (Liquid to Gas) is the boiling point of the liquidGravity – prevents escape of gasesGas would escape to space if not for the Earth’s gravity
19 Plasma Hot ionized gas with energy temperatures above 5000°C Violent collisions cause electronsto be knocked offStars, lightning, neon signs,solar wind, auroras, comet tails,welding arcs, fireball made bynuclear weapons
22 Conservation of Matter and Energy During an ordinary chemical change, there is no detectable increase or decrease in the quantity of matter.LAWEnergy cannot be created or destroyed, it can only change form.
23 Condensation – Gas to a Liquid Releases Thermal Energy
24 Freezing - Liquid to a Solid Releases Thermal Energy Freezing is an exothermic process
25 Melting - Solid to a Liquid Absorbs Thermal Energy For water the temperature has to be a little over zero degrees Celsius. If you were salt, sugar, or wood your melting point would be higher than water.
26 Evaporation – Liquid to a Gas Absorbs Thermal Energy
27 Sublimation – Solid to a Gas Absorbs Thermal Energy Skip a Phase: Solid to a GasCarbon dioxide (dry ice), Naphthelene (moth balls) and snow sublime
28 *** Condensation & evaporation are opposite (type error)
29 Absorb or Release Thermal Energy? Which phase is missing on this diagram?