HEAT AND ENTHALPY

HEAT AND ENTHALPY

Ø Reactions that release heat are exothermic

Ø Reactions that absorb heat are endothermic

Ø Heat is a form of energy

Ø ENTHALPY - Stored energy

Ø Enthalpy of gasoline > Enthalpy of water

Ø Enthalpy symbol is H and change in enthalpy is ΔH

ENTHALPY GRAPHS:

EXAMPLES:
EXOTERMIC-
2C8H18 + 25O2 -----> 16 CO2 + 18H2O + 5076 kJ
2C8H18 + 25O2 -----> 16 CO2 + 18H2O ΔH= - 5076 kJ
ENDOTHERMIC-
3.2 C + 2H2 + 52.3 kJ -----> C2H4
3.2 C + 2H2 + -----> C2H4 ΔH= - 5076 kJ

MORE Practice:
State whether each of the following are exothermic or endothermic.
a.) H + Cl ---> HCl + 432 kJ EXOTHERMIC
b.) 12CO₂ + 11H₂O ---> C1₂H₂2O11 + 12 O1₂ ΔH= 5638kJ ENDOTHERMIC