# Chem 2

 used to develop criteria for predicting the direction of a chemical reaction is the reaction spontaneous? occuring on it's own without added work? and Time? Thermodynamics and Kinetics Study of heat and work Thermochemistry energy that is transferred by system-surrounding until thermal equilibrium is established. (not state functions) heat (q) energy transfer between system and surrounding but results in (w=fxd) movement. (not state functions) Work (w) the universe surroundings specific part of the universe that is of interest system 3 types of system open, closed and isolated matter and energy transfer can occur between system and surroundings open only energy transfer can occur. Ex: earth Closed no matter or energy transfer can occur ex. thermos bottle q+w isolated depends of the present state of the system not how it got there. (final + initial condition) state functions measures the energy absorbed or released as heat in a chemical or physical change Calorimeter absorbs energy endothermic releases energy, system releases energy to the surrounding exothermic measure of avg kinetic energy of the particles in a sample. higher the temp, molecules move faster KE = 1/2 mv^2 Temperature amount of heat reqd to change temp. (intensive) always constant, the mass/ change in temp is a ratio. heat=mass x change in temp x specific heat capactiy (J) (g) (deg C) (J/g deg C) specific heat capactiy (cp) measure of systems capactiy to take up heat (extensive property) C=q/change in temp Heat capacity (C) Law of conversion of energy. energy cannot be created nor destroyed. qsyst + qsurr= 0 qsyst = -qsurr First law of thermodynamics Energy = q+w q>0 toward the system (endo) heat absorbed w>0= work done on the system by the surr. q<0 away from the system (exo) heat released w<0= work done by the system on the surr H(heat of rxn)=u + pv -measured using a calorimeter enthalpy energy available to do work gibbs free energy (delta G) delta H= Hfinal - H initial delta H>0 endothermic delta H<0 exothermic directly proportional to the amount of reactions/products involved enthalpy of reaction (delta H) allow chemists to find "H" (enthalpy) for reactions that cant be perfomed directly Hess's Law in any spontaneous process, the entropy (s) "disorder" of the universe is increasing. and remains unchanged in an equilibrium process. 1. s0 Spontaneous free energy delta G if (-) spontaneous if (+) non spontaneous if (=0) equal delta G=delta H-TdeltaS (for S to be negative, temp needs to be low) Gibbs free energy delta H <0, delta H>0 delta S <0, delta S>0 all depends on temperature Factors that can change a non spontaneous rxn to spontaneous rxn: Tempcouple a ns rxn with one that is spontpressure every substance has a finite(f) entropy, but at zero Kelvin, the entropy may become zero as in the case of a perfect crystal 3rd law of thermodynamics speed of any change over a period of time amount of mol (react)/ time rate atoms, ions and molecules react to form products when they collide provided particles have enough kinetic energy. collision theory factors affecting reaction rates Temp-energy move fastercatalystconcentration-the more qty the more reactionparticle size-the more you have---> rxn faster if stress is applied to a system in dynamic equlibrium, the system changes to relieve the stress Le Chateliers principle 3 types of stresses change in R/Pchange in tempchange in P/ change in V (gases) Authordee3215 ID19359 Card SetChem 2 DescriptionThermodynamics and Kinetics Updated2010-05-15T18:50:56Z Show Answers