Ch+12+-+Laws+of+Therm

__**Laws Of Thermodynamics**__

 * There are two laws of thermodynamics.
 * The first law deals with work and heat.
 * The second law states that we cannot get a greater amount of energy out of a cyclic process than we put in. There is no way to break even.
 * The First Law
 * Equations for work and heat: ΔU = Q - W
 * As heat is added to the system it does and equal amount of work, this allows it to follow the conservation of energy.
 * Q is the heat added to the system. W is the net work done by the system. U is the change in internal energy.
 * Q - W is the same for all paths connecting the final and initial states.
 * Work is caused by a pressure and a change in volume
 * Equation is: W = PΔV
 * Area under a PV graph is Work
 * [[image:PVGraphs.png]]
 * In graph A, the pressure drops and then the volume expands at a constant pressure.
 * In graph B, the volume expands and then the pressure is reduced at a constant volume.
 * In graph C, pressure and volume change continuously.
 * Thermodynamic Processes
 * Isobaric - Constant Pressure
 * Isochoric/Isovolumetric - Constant Volume
 * Isothermal - Constant Temperature
 * Adiabatic - No Heat Involved


 * Systems
 * Have some internal energy (U)
 * Doesn't have heat (Q) or work (W)
 * Systems change when Q is added or removed, or when W is done on it by a thermal process
 * Isothermal Process
 * U = (3/2)nRT
 * Second Law
 * Heat engines
 * Converts internal energy to other forms such as mechanical or electrical
 * Carries a substance through a cylindrical process
 * Process:
 * Energy (heat) is transferred at a high temperature. Then work is done by the engine, and finally the energy (heat) is expelled by the engine at a low temperature.


 * Cyclical Process
 * Work is area enclosed on a PV graph
 * Thermal efficiency