Ch. 11 -- Why Chemical Reactions Happen

spontaneous process

process occuring w/t outside intervention when started

nonspontaneous process

process occuring if energy is continually added to system

enthalpy

Delta H

• endothermic when delta H > 0 = reaction spontaneous

1st law of thermodynamics

energy is conserved and changes forms

entropy (S)

how dispersed energy in a system is bc of specific temp

• more disorder = higher entropy

• energy distribution affected by molecular motion, volume

2nd law of thermodynamics

entropy of universe increases in ALL spontaneous process

microstate

unique distribution of particles among energy levels

factors affecting entropy

• increasing temp

• increasing volume

• increasing # of idenpendent particles

Boltzmann Equation

S=k_{b}\ln W 

• S = entropy

• k_{b = Boltzmann constant (1.38 × 10^-23}) 

  • W = # of microstates

3rd law of thermodynamics

entropy of perfect crystal is 0 at absolute zero

reversible process

process that can run in reverse direction so that when system is restored to og state, no net energy has flowed to system nor surrounding

Gibbs Free Energy

maximum energy released by process occuring at constant temp and pressure available to do work

• refers to enthalpy, entropy, and temp for process

glycolysis

series of reaction that converts glucose into pyruvate

phosphorylation

reaction resulting in addition of phosphate group to organic molecule

ATP

can be used to drive nonspontaneous reactions