MARCH 21 st 2013

Energy Types  Electrical / Magnetic (light, magnetic fields)  Chemical (food, batteries)  Thermal (heat)  Nuclear (fission, fusion)  Kinetic (motion)  Potential (resting, stored up)

Kinetic Energy is entire objects travelling in a particular direction. Thermal Energy measures how each and every atom is wiggling or bouncing randomly all the time. KE vs. TE

Temperature measures the AVERAGE kinetic energy. Molecules will follow a distribution surrounding the average related to a STANDARD DEVIATION. Temperature vs. Energy Distribution

States of Matter TypeChange Shape?Expand to Fill Container? SolidNo LiquidYesNo GasYes Plasma*Yes *Plasma has enough Thermal Energy to separate electrons from the nucleus. **Atoms have insignificant volume and undergo elastic collisions. Match the diagram above with the description below.

Solids Packed tightly together. Held in place by chemical bonds. ‘Vibrate’ in place. May be crystalline in structure. May take multiple forms (allotropes)

Liquids Tend to stick to similar molecules (Surface tension due to intermolecular forces). ‘Wiggle’ and move around so long as touching other molecules. Have a vapor pressure which is positively correlated to temperature. Vapor pressures are the equilibrium between liquid and gas within a closed system at a certain temperature.

Gases Moves freely with or without contact from other atoms. ‘Bounces’ around in-between walls of container. Molecules are moving the fastest. Collisions w/ container cause pressure. Atmospheric pressure is defined as: 1 atm 760mm Hg kPa Plasma is a special gas where e - get removed from their orbits and go free. Examples: lightning, fluorescent lights, stars Subject to forces from electric and magnetic fields. Plasma

Solid LiquidGasPlasma Less EnergyMore Energy ColderHotter Melting Evaporating Ionizing Boiling Vaporization Sublimating FreezingCondensing De-Ionizing Fusion Phase Changes De-sublimating

Phase Diagram

Vapor Pressures

Heat Transfer 1)Radiation: The hot object ‘glows’ (visibly or invisibly) and energy leaves as light, or photons. Example: campfire, toaster oven, microwave, laser 2) Conduction: High-speed atoms (hot) hit touching atoms like bumper cars, and transfer their momentum and thermal energy directly. Example: ice-cubes, stove -> skillet -> food, hot pavement -> feet 3) Convection: High-speed atoms spread out and mix with cooler atoms, increasing the overall average energy. Examples: HVAC, hot and cold water spigots, hair dryer

Physics of Heating Latent Heat (L) is the amount of energy required to cause a phase change. Equation: Q = m L Units: Q = heat in Joules, m = mass in grams, L = Latent heat in J/g Specific Heat Capacity (C) defines how much temperature is affected by heating within a particular phase. Equation: Q = m C ∆T Units: same, C = specific heat capacity in J/(g *K) Material Freezing Point Boiling Point Solid Specific Heat Capacity (C s ) Liquid Specific Heat Capacity (C s ) Gas Specific Heat Capacity (C s ) Latent Heat of Fusion (Lf) Latent Heat of Vaporization (Lv) Water273*K373*K2.11 J/g *K4.18 J/g *K2.08 J/g*K334 J/g2260 J/g Ammonia195 *K240 *K? (use 4.6)4.6 J/g *K2.17 J/g *K339 J/g1369 J/g Ethanol159*K352 *K2.41 J/g *K2.43 J/g *K1.70 J/g * K109 J/g838 J/g

Starter Gas Laws Charles’ Law V 1 / T 1 = V 2 / T 2 when P stays the same Boyle’s Law P 1 V 1 = P 2 V 2 when T stays the same Gay-Lussac’s Law P 1 / T 1 = P 2 / T 2 when V stays the same

Ideal Gas Law P V = n R T P = pressure V = volume n = number of moles (groups of 6.02 * atoms or molecules) R = 8.31 L*kPa/(mol *K) called the universal gas constant T = temperature in Kelvin Measure in kPa for pressure, Liters for volume, moles for n, and Kelvin for temperature.

Guided Practice Problems 1)If I have a jar of air at 293 *K which has a pressure of 10 Pascals, and I place it in boiling water and let it reach thermal equilibrium, what will the new pressure be (assuming it does not expand)? 2)If I have a balloon at sea level, which I carry up a mountain until it is twice the size, what do I know about the air pressure at that elevation on the mountain? 3)A motor piston has a pressure of 100,000 Pa on both sides before the fuel ignites. Then the fuel temperature on one side goes from 293* K to 373* K. 1)What does the pressure on the hot side do? 2)What is the net pressure on the piston? 3)If the piston has an area of.1 m 2, what is the force? 4) How much volume will 4g of H 2 occupy at 400*K and 1.5 atm?