AP Chemistry / Unit 4: Chemical Reactions
4.3 Representations of Reactions
Notes
Reactions can be shown with balanced equations, particle diagrams, and data tables. Particle diagrams must conserve atoms and match the coefficients.
Practice
A particle diagram shows 4 $\mathrm{H_2}$ and 2 $\mathrm{O_2}$ before the reaction. After it shows:
Ratio 2:1:2, nothing left over.
In a particle diagram, the number of each type of atom before and after must be:
Atoms are conserved.
3 $\mathrm{H_2}$ and 3 $\mathrm{O_2}$ react. What's left over?
3 $\mathrm{H_2}$ uses 1.5 $\mathrm{O_2}$.
Ready for more? Take the Unit 4 test.