Method One (Hess’s Law)

[Drew Myers 4G]

Can someone give a quick explanation of how to use Hess’s Law?

[Aarja Pavade 1H]

Hess's Law states that enthalpy changes are additive. Thus, the enthalpy change at each step of a multi-step reaction can be added to give the total enthalpy change. ex: delta Hrxn1 + delta Hrxn2= delta Hnet (adding reactions to obtain net reaction).

[505316964]

If you have two equations that can be added together to get the wanted composite equation, you can add the deltaHRXN of each equation to get the net deltahHRXN.

[smurphy1D]

Are the equations we add together ones we have to put together ourselves or will they usually be given?

[Alice Chang 2H]

https://www.khanacademy.org/science/chemistry/thermodynamics-chemistry/enthalpy-chemistry-sal/v/hess-s-law-example

Khan Academy pulling through with a worked example! If you're more of a visual learner, this might help.