6.5 Hess's Law: Finding ΔH of Any Reaction

Question 1

Hess’s Law

Answer 1

the enthalpy change of an overall process equals the sum of the enthalpy changes of its individual steps:
ΔHoverall = ΔH1 + ΔH2 + ··· + ΔHn

Question 2

Steps to calculate ΔH (3)

Answer 2

1. identify target equation, the step whose ΔH is unknown; note the amount (mol) of each reactant and product
2. manipulate each equation w/ known ΔH values so that the target amount (mol) of each substance is on the correct side of the equation
3. add to the manipulated equations and their resulting ΔH values to get the target equation and its ΔH