Kinetic Energy Us Potential Energy

Chapter 10: Energy Changes in Chemical Reactions Kinetic Energy vs. Potential Energy Kinetic Energy: Energy of motion Potential Energy: Energy associated with position or composition Thermal Energy: Associated with temperature Chemical Energy: Associated with positions of electrons and nuclei   Units of Energy: kg * m²/s² 1 J = kg * m²/s² 1 cal = 4.184 J 1 Kcal = 1000 cal 1 Cal = 1 kcal or 1000 cal 1 kWh = 3.60 * 10^6 J First Law of Thermodynamics The total energy of the universe is constant. AKA "The law of conservation of energy" Energy cannot be created or destroyed. It can only be transferred. Exothermic Process: Energy flows from the system to the surroundings. Endothermic Process: Energy flows from the surroundings into the system. Example Calculation: 15 Kcal * 1000 cal/Kcal * 4.184 J/cal = 62760 J 75.4 KJ * 10^3 J/KJ = 75400 J Δ means: change in Internal Energy (U) The sum of kinetic and potential energies of all particles in the system. A state function: value depends only on initial and final conditions. ΔU = Ufinal - Uinitial Reaction Diagram for C(s) + O₂(g) → CO₂(g) ΔUreaction = Uproducts - Ureactants ΔUsystem = -ΔUsurroundings ΔUsystem + ΔUsurroundings = 0 Energy Diagram Decreasing in product energy Our system loses energy Exothermic reaction Consider internal energy gases for a chemical system and its surroundings. Which diagram on the right represents the energy gauge for the same system and surroundings after an energy exchange in which ΔUsystem < 0? Decreasing the system ENERGY EXCHANGE between the system and the surroundings through heat and work. 9 = heat (thermal) energy HEAT 9 surroundings W work energy WORK W \[\triangle U=q+W\] \(\Delta U_{1}\) refers to the system. SIGN CONVENTIONS FOR GIW, AU 9(heat) + system gains thermal energy -system loses thermal energy w(work) +work done on the system - work done by the system AN(Change in +energy flows into the system -energy flows out of the system internal energy) PRACTICE. Identify if it's heat or work and determine whether the sign (relative to the system) is (+) or (-) • An ice cube melts and cools the surroundings beverage. (system = Ice cube). heat 9 (Something that changes) (+ because heat is going into the system) A metal cylinder is rolled up a ramp (system = metal cylinder). work W (+, work energy in the metal to go up the ramp). • Steam Condenses on skin, causing a burn (System = Sicam) heat 9-, steam giving off heat) A cylinder and piston assembly (defined as the system) is warmed by a flame. The contents of a cylinder expand, doing work on the surroundings by Pushing the piston out ward against the external pressure if the system absorbs 559 J of heat and does 488 J of work during the expansion, what is the value   for \(\Delta u\) ? \[\Delta U=q+\omega\] \(g=+559\) (absorbs is positive) \[=559J-488J\] \(w=-488J\) (14 + it's