energetics Flashcards
Formation ΔH
The enthalpy change when one mole of a compound is formed under standard states and standard conditions
Combustion ΔH
The enthalpy change when one mole of a compound reacts completely with oxygen in standard state and standard conditions
Neutralisation ΔH
The enthalpy change when a acid reacts with a base and forms one mole of H20 under standard states and standard conditions
Average bond enthalpy
The energy required to break one mole of a specific type of bond in a gaseous molecule.
How to work out enthalpy change with bonds
ΔH = Bonds broken -Bonds made
Hess’ law
If a reaction can take place by more than one route and the initial and final are the same, the enthalpy change will be the same
What way do the arrows point in ΔH formation reactions
They point up from the elements
What way do the arrows point in Combustion/Bond/Neutralisation
They point down from the reactants and products to the elements
How to work out molar enthalpy change
Q = MCΔT ΔH = Q/n
Endothermic reaction
Absorbs heat
Exothermic reactions
Releases heat
