potential energy
energy stored in chemical bonds
(chemical or nucear energy)
kinetic energy
energy assosiated with movement
(thermal, sound, mechanical, electrical)
high potential energy
attractions b/w electrons and protons
low potential energy
repulsions b/w nucleai or electrons
enthalpy/heat content
chemical energy of a substance
(H = Ep + Ek)
enthalpy change/heat of reaction
differenct in enthalpy of products and reactants
exothermic reactions
- negative enthalpy change
- enthalpy of products is less than reactants
- energy is released from reaction to the environment (immediate environment gets hotter, eg. reaction mixture)
eg. combustion
endothermic reactions
- positive enthalpy change
- enthalpy of products is more than reactants
- energy is absorbed from the environment to the reactions (immediate environment gets cooler, eg. reaction mixture)
eg. photosynthesis
activation energy
energy required to break bonds in the reactants
heat of combustion (Hc)
heat energy released when a specific quantity of substance burns completely in oxygen (combusts)
enthalpy of combustion (delta Hc)
enthalpy change when a specific quantity of substance combusts completely in oxygen
negative sign. WATER IS LIQUID
relationship b/w heat of reaction and heat of combustion
heat of reaction = heat of combustion x coefficient(fuel)
get from thermochemical equations. only works for combustion reactions
specific heat capacity
amount of energy required to raise the temperature of 1g of substance by 1 degree
higher the SHC more efficiently a material will store heat energy (lower temperature change)
low chemical energy
high stability -> high strength of bonds -> higher energy needed to break bonds
high chemical energy
low stability -> low strength of bonds -> less energy needed to break bonds
