P1: 5 Kinetics Flashcards
When can reactions occur?
When collisions take place between particles having sufficient energy (activation energy).
What is activation energy?
Minimum energy required for bonds to break and reactions to occur when particles collide.
Why do most collisions not lead to a reaction?
The particles don’t have E greater than or equal to Ea.
What does the area under a Maxwell-Boltzmann distribution curve represent?
Total number of molecules.
Why does a Maxwell-Boltzmann distribution curve start at (0,0)?
No molecules have zero energy.
What does the peak of a Maxwell-Boltzmann distribution curve represent?
Most probable energy of a molecule.
Where is the mean energy of the molecules on a Maxwell-Boltzmann curve?
To the right of the peak.
What is the rate of reaction?
Change in concentration of a substance over time.
What is the effect of temperature changes on the rate of reaction?
Increasing the temperature means many more molecules have E greater than or equal to Ea so there are more frequent successful collisions, increasing the rate of reaction.
What is the effect of changes in concentration/pressure on collision frequency?
Increasing the concentrations means there are more particles in a given volume so more frequent successful collisions, increasing the rate of reaction.
What is a catalyst?
A substance that increases the rate of a chemical reaction without being changed in chemical composition or amount.
How does a catalyst work?
They provide an alternative reaction pathway with a lower activation energy.
