1.6.5 Hess' Law Flashcards
1
Q
The products can be directly formed from the elements =
A
ΔH2
2
Q
The products can be indirectly formed from the elements =
A
ΔH1 + ΔHr
3
Q
The enthalpy change from elements to products (direct route) is equal to the enthalpy change of elements forming reactants and then products (indirect route)
A
4
Q
Equation
A
ΔH2 = ΔH1 + ΔHr
5
Q
Therefore
A
ΔHr = ΔH2 – ΔH1
6
Q
A
7
Q
A
8
Q
The enthalpy change of atomisation (ΔHatꝋ ) is the enthalpy change when
A
one mole of gaseous atoms is formed from its elements under standard conditions.
9
Q
Eg. ΔHatꝋ [H2] relates to the equation
A
½ H2(g) → H(g)
