1. LO: I understand what is meant by Hess’s law.

2. Hess’s law states that the enthalpy change for a reaction is dependent on the reactants and products and not on the route taken.
For example:
H1 C +
2H2
CH4
+ O2
+ O2
+ 2O2
H2
H3
H4
CO2 +
2H2O
H1 =
H2 +
xH3 -
H4
LO: I understand what is meant by Hess’s law.

3. Calculations Involving Hess’s Law
LO: I know how to calculate enthalpy changes using Hess’s law.

4. Calculate the enthalpy of formation of Silane (SiH4).+
Hf
Hc(silicon) = -911 kJmol-1
Hc(silane) = kJmol-1
Hc(hydrogen) = -286 kJmol-1
Hf
Hc(reactants)
Hc(products)  
 x-286)
-1517)  
34 kJ mol-1 
LO: I know how to calculate enthalpy changes using Hess’s law.