1. Heats of Formation

2. Definition
ΔHf – energy change associated with the formation of compound from its constituent elements
Standard Heat of Formation - ΔHfº - heat of formation of a material in its standard state (most stable form)
See Appendix Four (pg. A19)

3. Examples What is the equation and heat of formation for:
a) acetylene (C2H2)
b) silver chloride
● ΔHfº for an element is zero

4. Calculating Heats of Reaction
Δ Hrxn = ∑nΔHfº(product) - ∑mΔHfº(reactant)
Find the heat of reaction for:
C6H12O6 + 6O2 → 6CO2 + 6H2O

5. Example
Compare the quantity of heat produced by the combustion of 1.00 g of glucose with that produced by 1.00g of sucrose.

6. Example
The standard enthalpy change for the reaction: CaCO3 → CaO + CO is kJ. From the value of ΔHfº for CaO and CO2, calculate the ΔHfº for CaCO3 .