Reaction Rates Flashcards
What is the equation used to calculate rate?
Rate = change in conc / time
What is the unit for the rate of reaction?
mol dm-3 s-1
What must particles do in order to react?
Collide with sufficient energy (activation energy)and the correct orientation.
Do most collisions result in a reaction?
No
What are the factors that affect rate of reaction?
- temperature
- pressure
- concentration
- surface area
- catalyst
What are the variables in an experiment that can be monitored to calculate the rate of reaction?
- conc of reactant or product
-gas volume of products - mass of substances formed
What is a catalyst?
A substance which increases the rate of reaction but is not used up in the reaction.
How do catalysts work and how do they increase the rate of reaction?
They provide an alternate reaction pathway. Due to lower activation energy, more particles have energy > activation energy, so more frequent successful collisions, so increased reaction rate.
What does homogeneous catalyst mean?
A catalyst that is in the same phase as the reactants.
What does heterogeneous catalyst mean?
Catalyst used in the reaction is in different phase to the reactants.
What are catalytic convertors?
They are present in vehicles to reduce toxic emission and prevent photochemical smog.
Define activation energy
The minimum energy that particles must collide with for a reaction to occur.
Name some important features of Boltzmann distribution (5).
- Area under the curve = total no. Molecules
- Area under the curve does not change when conditions alter
- The curve starts at the origin
- Curve does not touch or cross the energy axis
- Only the molecules with energy greater than activation energy can react
What are the axis in a Boltzmann distribution?
X axis — energy
Y axis — no. Molecules with a given energy
