Controlling the Rate Flashcards
Why should rate be calculated?
if slow, the process isn’t economical
if fast, risk of explosions
What must happen for chemical reactions to occur
Particles must collide with :
- correct orientation
- enough energy to produce product
What are the 5 main factors that affect rate
particle size
temperature
concentration
Pressure
Catalyst
How does decreasing particle size increase ROR
more surface area is available for collisions to occur
How does increasing concentration increase ROR
more collisions occur as more particles are present in the same volume
How does increasing temperature increase ROR
more particles have enough energy for a reaction to happen when they collide
- higher temperature = more collisions
How does increasing pressure increase ROR
particles are compressed together causing more collisions
How does a catalyst increase ROR
lowers amount of energy needed for a successful reaction
What is activation energy
the minimum energy required for a reaction to happen
What happens when reactants collide with activation energy
an unstable intermediate (ACTIVATED COMPLEX) forms which breaks down into products
Where on a graph is activation energy measured
from reactants to the top of the bump
Where on a graph is enthalpy change measured
from reactants to products
What is a measure of average kinetic energy of particles
temperature
For exothermic reactions, is enthalpy change positive or negative
negative
For endothermic reactions, is enthalpy change positive or negative
positive
