Physical Science / Unit 5: Chemical Reactions
5.6 Reaction Rates
Notes
The reaction rate is how fast reactants turn into products. Reactions need particles to collide with enough energy.
- Higher temperature: particles move faster, collide more often and harder, so the rate increases.
- Higher concentration: more particles in the same space, so more collisions.
- Greater surface area (smaller pieces): more exposed particles. Powdered sugar burns faster than a sugar cube.
- A catalyst speeds up a reaction by lowering the activation energy and is not used up. An inhibitor slows a reaction.
Practice
Why does crushing an antacid tablet make it dissolve faster?
More particles are exposed to collisions.
Which change would slow down a reaction?
Cooler particles move slower and collide less often.
What does a catalyst do?
Catalysts speed up reactions and are regenerated.
Ready for more? Take the Unit 5 test.