thermochemistry 2
Terms
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- thermochemistry
- the study of the transfers of energy as heat that accompany chemical reactions and physical changes.
- calorimeter
- measures the energy absorbed or released as heat in a chemical or physical change.
- temperature
-
a measure of the average kinetic energyof the particles in a sample or matter.
measurement of heat. - joule
- the SI unit of heat as well as all other forms of energy.
- heat
-
- direction of energy
- transfer of heat
- high --> low
- you never get cold, you only lose heat - specific heat
-
the amount of energy required to raise the temperature of one gram of substance by one celcius degree or by one kelvin.
- conductors and insulators
- conductors = low specific heat ex. gold, lead
- insulators = high specific heat (holds onto energy) ex. water, glass - Cp= q/(m * delta T)
- specific heat (J/g*K) = energy lost or gained (J)/ mass(g) * change in temp
- heat of reaction
- the quantity of energy released or absorbed as heat during a chemical reaction. (kJ/mol)
- thermochemical reaction
- an equation the includes the quantity of energy released or absorbed as heat during the reaction as written.
- enthalpy change
- the amount of energy absorbed or lost by a system as heat during the process at constant pressure
- exothermic reaction
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- energy is released
- the q is negative - endothermic reaction
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- energy is absorbed
- the q is positive
- tend to be more unstable - molar heat of formation
- the energy released or absorbed as heat when one mole of a compound is formed by combination of its element.
- enthalpy change/ delta H of elements in their standerd state
- 0
- heat of combustion
- the energy released as heat by the complete combustion of one mole of a substance.
- hess's law
- the overall enthalpy change in a reaction is equal to the sum of enthalpy changes for the individual steps in the process.