C2.4 Rates of Reaction Flashcards
What two measures can form the rate of reaction?
The rate at which reactant is used up
The rate at which product is produced
How do you calculate the rate of reaction?
Rate of reaction =
Amount of reactant used / product formed
———————————-
Time taken
What is the rate of reaction if 24cm3 of Hydrogen is produced in 2 minutes?
Product formed / time taken
24 / 2 = 12cm3 of hydrogen produced per minute
What factors can increase the rate of reaction?
- increased temperature
- increased concentration of REACTANT
- increased pressure of REACTANT
- Catalyst
- Smaller sized pieces of REACTANT
What does a steep line on a graph of product v time suggest?
A fast rate of reaction
When will the reaction be at its fastest and why?
Usually at the BEGINNING
This is because this is when the concentration of the REACTANT is at its highest
What is the activation energy?
The minimum energy required when two particles in a reaction collide in order for them to react
Why does an increase in concentration or pressure of the reactants cause the rate of reaction to increase?
There are more particles in the same volume so the likelihood of collision is more likely / collisions happen more frequently
This causes the rate of reaction to increase
Why does a smaller particle size of the reactant increase the rate of reaction?
The surface area of the reactant is increased meaning more of it is exposed to the opposing reactant. This increases the likelihood of the two different reactants colliding and increases the rate of reaction
How does an increase in temperature increase the rate of reaction?
- The increased heat energy causes the reactant particles to move more quickly
- More particles now have the activation energy
- Collisions are both more frequent and also more successful
- The rate of reaction increases
How does a catalyst increase the rate of reaction?
They lower the activation energy needed
Why are catalysts useful?
They increase the rate of reaction so less reactants are needed for a longer amount of time
This means the industry can save money
