Thermochem

heat

form of energy

thermochemistry

studies the heat and energy changes associated with chemical reactions

exothermic reaction

reaction releases energy -H

endothermic reaction

reaction absorbs energy

enthalpy

heat enrgu absorbed or released by a reaction

formula for enthalpy change

H=Hp-Hr

hess law

depends only on the intial and final states and not on the path of the reaction

steps to hess law

1. if necessary reverse equations so products and reactant are on appropiate sides

2. if a reaction is reversed YOU MUST CHANGE the sign of Hf

3. get correct amounts as original reaction

4. cancel

calorimetry

process of measuring heat

heat capacity

number of heat units needed to raise temp one degree

specific heat

heat required to raise the temp of the unit mass of a given substance

formula for calculating heat

q=mxcxDiff in T

gibbs free enrgy G

energy available to do work (measered in KJ/mol)

formula for calculating free energy

G=Gp-Gr

G-H-T(S)

entropy

a measure disorder/chaos (measured in j/mol K)

formula for entorpy

S=Sp-Sr

activation energy

energy needed to start a reaction and form activate complex

increasing entropy +S

decreasing entropy -S

thermodynamically favourable/spontanious

occurs w/o outside help -G