2. 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

3. Basic Energy TypesBasic Energy Types 1)Kinetic Energy– energy of “motion” 2)Potential Energy– “stored” energy

4. Work (w)Work (w)  = FORCE x DISTANCE  w = -P Δ V  How much force is needed to move an object a certain distance  Unit—Joule (J)

5. 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

6. System vs. SurroundingsSystem vs. Surroundings

7. 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

9. Internal Energy (U)Internal Energy (U)  Energy within a system (kinetic energy + potential energy)  Mostly made up of chemical bonds and intermolecular forces

10. 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”

11. 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

12. State Function ( Δ )State Function ( Δ )  Property with a specific value only influenced by a system’s present condition  Only dependent on the initial and final states, NOT on the path taken to reach the condition  Initial state Final state  Δ U = U final – U initial ** State functions go back to initial values in opposite process and system returns to initial state**

14. 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 = Σ energy of its components  Δ U = q + w, Δ E total = Δ E sys + Δ E surr = 0

15. Homework  p. 250 #2, 3, 19, 22