enthalpy Flashcards
define enthalpy
the measure of the heat energy in a chemical system
how do you calculate enthalpy change?
enthalpy change = H(products) - H(reactants)
define conservation of energy
energy cannot be created or destroyed
exothermic change
heat out of the system to the surroundings (negative enthalpy change)
endothermic change
heat into the system from the surroundings (positive enthalpy change)
activation energy
the minimum energy required for a reaction to take place
standard conditions
100kPa
298K
1 mol dm-3
standard state
the physical state of a substance under standard conditions (RTP)
enthalpy changes of reaction
the enthalpy change that accompanies a reaction in the molar quantities shown in a chemical equation under standard conditions
enthalpy of formation
enthalpy change when 1 mole of a compound is formed from its constituent elements under standard conditions with everything in its standard state
enthalpy of combustion
enthalpy change when 1 mole of fuel reacts completely with oxygen under standard conditions with everything in its standard state
enthalpy of neutralisation
the energy change that accompanies the reaction of an acid by a base to form one mole of H2O (l) under standard conditions with everything in its standard state
