Final exam room – Chemistry A103
2 lectures left
Final model assignment
Due beginning of class on Friday
Can certainly turn in early
This week’s due date is tomorrow at 5 pm
Office Hours Friday in Yates 103
Check RamCT for
Finals week office hours
Final Exam rooms
Calculating ΔH rxn
Remember, H is a state function
ΔH rxns only based on intial and final states
Therefore, we can picture any process for a reaction
The simplest is to think of all bonds breaking then reforming
This is not what actually happens but it works
The ΔH formula
ΔH rxn ΣΔH bonds brokenH bonds formed
Recall, Σ → sum of
Signs are essential
Clicker question If a reaction is endothermic, what does that say about the relative stability of the
products vs. the reactants?
A. You cannot make a statement regarding their stability.
B. Products are more stable.
C. Products are less stable.
Low energy → more stable
Endothermic → takes energy to get to products
CH (4) + 2O (g2 → CO (g) +22H O (g)