1. Thermochemistry

2. What’s the difference?

3. Enthalpy (H) Heat content of a chemical system.
DH = “change in enthalpy”
DH = Hproducts – Hreactants
DH can be + (heat is absorbed)
DH can be – (heat is released)

4. Predict the products: CaO + H2O  ? Ba(OH)2 + NH4Cl  ?
Write your observations of the reaction.
Ba(OH)2 + NH4Cl  ?

5. If DH is + Reaction absorbs heat.
Products have higher enthalpy than reactants.
Reaction is ENDOTHERMIC.

6. If DH is - Reaction releases heat.
Reactants have higher enthalpy than products.
Reaction is EXOTHERMIC.

7. Summary: CaO + H2O Ca(OH)2+ heat ΔH = negative, exothermic
Heat + Ba(OH)2 + 2NH4Cl  BaCl2 + 2NH4OH ΔH = positive, endothermic