Thermodynamics - L4 thermochemistry

H gen chem 1

every chemical reaction is accompanied by

a change in energy

complete reaction with oxygen is called

combustion

thermochemical equation

a chemical equation together with a statement of the reaction enthalpy

reaction enthalpy

the associated enthalpy of a reaction

the enthalpy change for a reverse process

is the negative of the forward process

standard state

a reactant/products pure form at 1 bar

standard reaction enthalpy

the reaction enthalpy when reactants in their standard states change into products in their standard states

standard enthalpy of combustion

the change in enthalpy per mole substance burned in a combustion reaction under standard conditions

specific enthalpy

the standard enthalpy of reaction divided by the mass of the sample

enthalpy density

the enthalpy of reaction of a sample divided by the volume of the sample

hess’s law

the total enthalpy change for a chemical reaction is the same, regardless of the number of steps it takes, as long as the initial and final conditions are the same

standard enthalpy of formation

the standard reaction enthalpy per mole of formula unit s for the formation of a substance from its elements in their most stable form

it always takes energy to

break bonds

bond breaking is always

endothermic

for reactions in which no gas is generated or consumed

little expansion work is done and the different between the change in internal energy and enthalpy is negligible