Experience Chemistry 12.2: The Progress of Chemical Reactions

​Lesson 12.2: The Progress of Chemical Reactions

Multiple Choice

What is the rate of reaction?

• How fast a reaction is 
• How big a reaction is
• How loud a reaction is
• How much gas a reaction produces

Multiple Choice

In an endothermic reaction, heat is ...

• taken in or absorbed
• given out or released 

Multiple Choice

Exothermic reactions...

• Absorb energy
• Release energy
• Release Color
• Absorb Color

Multiple Choice

What two factors govern whether a collision between reacting particles will be effective?

• orientation and direction

• energy and orientation

• temperature and kinetic energy 

Multiple Choice

Increasing the concentration of the reactants will slow down the reaction.

• false 
• true

Multiple Choice

Why does a higher temperature increase the rate of a reaction?

• it increases both the frequency and energy of particle collisions
• it only increases the frequency of particle collisions
• it only increases the energy of particle collisions
• it reduces the activation energy of the reaction

​Activation Energy

• When reactants collide, they need a certain amount of energy for a reaction to take place

• Activation energy: the minimum energy requirement for colliding particles to react​

  • A barrier that reactants must overcome before products can form​

Experience Chemistry | Lesson 12.2

​Activation Energy

Experience Chemistry | Lesson 12.2

​Energy Diagrams

• The Activated Complex is the transition state between reactants and products

• Shown in a graph of the energy over the course of a reaction​

Experience Chemistry | Lesson 12.2

​One-Step and Multistep reactions

• Some reactions take place in a single step, but most are multistep reactions

• Reaction Intermediate: the product of one step in a multistep reaction and the reactant in another step

  • Consumed in the formation of the final products​

• For multistep reactions, the slowest reaction is the rate-determining reaction

  • slow reactions have low energy, fast reactions have high energy

Experience Chemistry | Lesson 12.2

​One-Step and Multistep reactions

Experience Chemistry | Lesson 12.2

Multiple Choice

The minimum amount of energy needed for colliding particles to react is called the

• Chemical Energy

• Kinetic Energy

• Activation Energy

• Potential Energy

​Lowering Activation Energy

• There are several methods to speed up a reaction that don't affect the activation energy

  • Increase Temperature, Increase Concentration, Reduce Particle Size

• ​There are two main methods to speed up a reaction by decreasing the activation energy

  • Catalysts

  • Enzymes​

Experience Chemistry | Lesson 12.2

​Catalysts

• Catalyst: A substance that increases reaction rates by reducing the activation energy

  • ​Is NOT Consumed in the reaction

  • Can be reclaimed and reused in some reactions

• Two types of catalysts

  • Homogenous Catalysts: in the same phase state of the reactants and products

  • Heterogenous Catalysts​: in a different phase than the reactants and products

    • Are often metals

Experience Chemistry | Lesson 12.2

​Catalysts

Experience Chemistry | Lesson 12.2

• Catalysts create an alternate, lower path for a reaction to take place

​Enzymes

• Some reactions take place in living systems and are limited in what factors can be changed

• Enzymes: Proteins or other molecules that serve as biological catalysts by folding into shapes to form active sites

  • The enzyme bonds with the reactants to form an intermediate complex

  • Positions the reactants so they are in the correct orientation for the reaction

Experience Chemistry | Lesson 12.2

​Enzymes

Experience Chemistry | Lesson 12.2

Multiple Choice

A substance that increases the rate of a reaction without being used up during the reaction is called a

• catalyst

• product

• reactant

• solute

Multiple Choice

How does a catalyst work in speeding up a reaction?

• By lowering the activation energy or reaction

• by giving them more energy

• by making them more available

Multiple Select

Select four factors that affect the rate of a reaction

• temperature

• concentration

• surface area

• volume

• The presence of catalysts

Multiple Choice

Which of the reaction pathway shows the catalysed reaction?

• 1

• 2