Energy Ability to do work Units Joules (J), we will use kJ Can be converted to different types Energy change results from forming and breaking chemical bonds in reactions Basic Energy TypesBasic Energy Types 1)Kinetic Energy energy of motion 2)Potential Energy stored energy Work (w)Work (w) = FORCE x DISTANCE w = -P V How much force is needed to move an object a certain distance UnitJoule (J) Elastic vs. Inelastic Collisions Elastic collisions No energy is lost Potential and kinetic energies are constant. Kinetic energies added together Inelastic collisions Some energy is lost with each collision Potential and kinetic energies are not constant System vs. SurroundingsSystem vs. Surroundings Types of SystemsTypes of Systems 1)Open System Full interaction between system and surroundings matter and energy exchange 2)Closed System Partial interaction between system and surroundings Energy exchange, NOT matter 3)Isolated System No interaction between system and surroundings NO matter and NO energy exchanges Internal Energy (U)Internal Energy (U) Energy within a system (kinetic energy + potential energy) Mostly made up of chemical bonds and intermolecular forces Heat (q)Heat (q) Energy transfer between a system and the surroundings due to a temperature change Gain/loss of energy Transfer is instantaneous from high----low temperature until thermal equilibrium Measured in joules (J) Temperature Measure of heat, hot/cold Heat (q) continuedHeat (q) continued Kinetic theory of heat Heat increase resulting in temperature change causes an increase in the average motion of particles within the system. Increase in heat results in Energy transfer Increase in both potential and kinetic energies State Function ( )State Function ( ) Property with a specific value only influenced by a systems present condition Only dependent on the initial and final states, NOT on the path taken to reach the condition Initial state Final state U = U final U initial ** State functions go back to initial values in opposite process and system returns to initial state** 1 st Law of Thermodynamics (Conservation of Energy) Energy cannot be created or destroyed. With physical and chemical changes, energy can be transferred or converted. Total energy = energy of its components U = q + w, E total = E sys + E surr = 0 Homework p. 250 #2, 3, 19, 22