Quiz Review Key

Name: Key Period:

Unit 10 Quiz Review 1. Define the following terms: a. Reaction Rate

the amount of time it takes to convert the reactants to products b. Collision Theory

Theory that describes how reactions happen: In order for molecules to react, they must collide with the correct orientation and with sufficient energy c. Activation Energy

The minimum amount of energy required to get a reaction to occur. The higher the activation energy, the slower the reaction. *need to know how to find AE on energy diagram d. Energy Diagram

A graph that shows how energy changes over the course of the reaction. *need to know what the energy diagram for endo and exo look like e. Catalyst

A substance that reduces that activation energy for a reaction without being consumed by the reaction. Adding a catalyst increases the reaction rate. f. Equilibrium

Rate of the forward reaction is equal to the rate of the reverse reaction.

g. Le Chatelier’s Principle

If a system at equilibrium experiences a change in concentration or temperature, then the equilibrium will shift so as to oppose the change. 2. Describe how the following changes would affect reaction rate. Explain using the Collision Theory. a. Increasing temperature

If you increase the temperature, the molecules will be moving faster so they will collide more often and with more energy. This causes the reaction rate to increase. b. Decreasing concentration

If you decrease the concentration, you have less molecules. Less molecules means less collisions will occur, which will decrease the reaction rate. c. Adding a catalyst

A catalyst lowers the activation energy, which will make the reaction rate increase. d. Increasing the surface area of the reactant

If the surface area is increased, there are more molecules exposed at the same time. If more molecules are exposed, more collisions can happen, which increases the reaction rate. 3. Given the following chemical reaction at equilibrium, predict how the equilibrium will shift if the following changes are made. X2 + Y2 + heat  2XY a. temperature is increased

Shift to the product side

b. X2 is added to the system

Shift to the product side c. XY is added to the system

Shift to the reactant side d. Y2 is removed from the system

Shift to the reactant side