You should be able to give a one sentence definition of what a catalyst is. From there you should know the effects that catalysts have on rates of reactions and how it doesn’t effect the equilibrium of the reaction.
Background Summary:
What are Rate of Reactions? http://www.chem4kids.com/files/react_rates.html
Rate of reactions are the speed at which a reaction happens.
- If a reaction has a lower rate of reacting that means that the molecules take longer to collide together.
- If a reaction has a higher rate of reacting that means that the molecules collided together a lot faster.
What is the Collision Theory http://www.chem4kids.com/files/react_rates.html
The collision theory says that the more collisions in a reaction the more combination of other molecules that will bond together. When there are more successful collisions in rate of reactions the faster the molecules will react and the higher the rate of the reaction will be.
more successful collisions = more combination of molecules = the faster molecules will react = the rate of the reaction will be higher
What is needed in order to have more successful collisions? http://www.saskschools.ca/curr_content/chem30_05/2_kinetics/kinetics2_1.htm
- The right amount of activation energy.
- The right orientation.
What other aspects influence the reaction? http://www.chem4kids.com/files/react_rates.html
What is Concentration?
Concentration is the amount of substance that is mixed in with another.
- The more concentration the molecules have the more likely they will collide together and increase the rate of the reaction.
- The less concentration the molecules have the more unlikely they will collide together and this will usually decrease the rate of the reaction.
Temperature
- When you heat up a molecule/molecules you are giving them more kinetic energy (which is more movement). The movement that you are giving them is making them move throughout their contained area. The more movement that you give them, the more likely they are able to bump into each other and collide together.
- The less heat each of these molecules have the more time its going to take for them to collide together.
What is Pressure?
Pressure is the force that is applied on a certain area.
- When you increase the pressure the molecules have less space to move around in, so the faster they can collide together.
- When you decrease the pressure the more space the molecules have to move around, so the slower they are going to collide together.
This flash animation that you are about to watch clearly shows what is needed in order for a successful collision to take place between molecules. It shows what will happen when you don't have all the requirements needed and when you do.
Lesson:
What is Activation Energy?http://www.chem4kids.com/files/react_catalyst.html
Activation energy is the amount of enegry needed for a successful collision to happen between molecules.
What are catalysts? http://www.chem4kids.com/files/react_catalyst.html
Catalysts are what accelerate the rate of the reaction.
As well as that catalysts lower the activation energy of the reaction. However catalysts don't effect the equilibruim of the molecules. Equilibruim is a stable situation when forces can cancel each other.
Click on Enzymes/Catalysts to see an example of a catalyzed object.
Now it's time to test your understanding of this concept?
Questions& Answer Time
1. What happens to the activation rate of the reaction when a catlyst is added?
1a. It decreases the activation energy.
b. It increases the activation energy.
c. The activation energy stays the same through the reaction.
d. non of the above
2. What is the definition of activation energy?
2a.Activation energy is the set amount of energy every molecule has in order for molecules to bond together.
b. Activation is the amount amount of energy that each molecule start out with.
c. Activation energy is the amount of energy needed for a reaction to successfully happen.
d. non of the above
3. What is a catalyst?
3a.A catalyst is what increases of the pressure of the reaction.
b. A catalyst is what accelerates the reaction.
c. A catalyst is a molecule.
d. non of the above
4. What effect does a catalyst have on the rate of reactions?
4a. It speeds up the reaction.
b.It slows down the reaction.
c.It keeps the reaction going at an average rate per second.
d.non of the above
5. Draw me the graph of activation energy in the rate of reaction, with and without a catalyst.
