Enthalpy Changes Flashcards
1
Q
what is the enthalpy change of a reaction?
A
the heat energy it releases or absorbs per mole
2
Q
what is the symbol for enthalpy change?
A
ΔH
3
Q
what sign is used for endothermic reactions and what does it tell us about the heat energy?
A
positive (+) and the heat energy has been absorbed
4
Q
what sign is used for exothermic reactions and what does it tell us about heat energy?
A
negative (-) and the heat energy has been released
5
Q
what does enthalpy change tell us?
A
- the value tells us how much heat energy is absorbed or released
- the units are always kJ/mol so that different reactions can be compared easily
6
Q
what does heat energy absorption or release depend on?
A
the balance between:
- breaking bonds, which absorbs energy
- making bonds, which releases energy
