Thermochemistry Study of transfers of energy as heat that accompany chemical rxns and physical changes Part 1

Energy The ability to do work or produce heat Potential energy = positional energy Kinetic energy = energy of motion The energy absorbed or released as heat in a chemical or physical change is measured in a calorimeter.

Heat Temperature = a measure of the average kinetic energy of the particles in a sample Heat = energy that transfers between samples due to a diff. in temperatures We measure heat is various units: calorie = amount of heat required to raise 1 gram of water 1 degree celsius Food Calorie = 1 kilocalorie [1 Calorie = 1000 calories] Joule (J) = the SI unit of heat and energy [1 calorie = 4.184 J]

Specific Heat Amount of energy required to raise 1 gram of a substance by 1 degree celsius Each substance has its own specific heat [see p503 figure 1.2] Specific Heat equation: q = m x c x DT q = heat m = mass c = specific heat DT = change in temperature (oC or K)

Specific Heats of Common Substances