Hess' Law Flashcards
1
Q
What is Hess’ Law?
A
Overall enthalpy change of a reaction is the same, independent of the route taken
2
Q
Which direction do the arrows point for the enthalpy change of combustion?
A
downwards
3
Q
Which direction do the arrows point for the enthalpy change of formation?
A
upwards
4
Q
How do you solve the Hess cycle, step by step?
A
- Rewrite the equation
- Identify the type (combustion or formation)
- Draw the diagrams
- Write the equation in terms of /\H
- Sub in the values
- Solve
5
Q
How do you solve /\Hr1 from /\Hr2 and /\Hr3?`
A
- Identify the key substances in /\Hr1 which are reactants/products in /\Hr2 and /\Hr3
- Draw arrows on /\Hr1 which match /\Hr2 and /\Hr3
