5.4

• Natuurkunde / Scheikunde
• Middelbare school
• havo
• Leerjaar 3

Learning Goals

• Explain what the difference is between exothermic and endothermic reactions.
  
• Describe some examples of exothermic and endothermic reactions.
  
• Define reaction rate.
  
• Define catalyst and explain its behavior in a chemical reaction.
  
• Describe how temperatures, concentration, and a catalyst affect the reaction rate. 

Forms of energy

• Heat
• Light
• Electricity
• Chemical
• Kinetic 

Different types of reactions:

• Exothermic

       Transfer energy to the                    surroundings

• Endothermic 

       Take energy from the                     surroundings

        

Name an exothermic reaction

Demonstratie verbranding

Name an endothermic process/reaction

Demonstratie soda + azijn

Rate of reaction

How does a reaction take place? 

(throwback to Theme 3, particle theory) 

How does a chemical reaction take place?

For a reaction to occur, the particles that are reacting must collide with each other. Only some of all the collisions that take place cause a chemical change to happen. These are called 'successful' collisions. The greater the number of 'successful' collisions, the faster the rate of a reaction. This is called the 'collision theory'.

What are the four factors that influence the rate (speed) of a reaction?

The four factors:

• temperature
  
• concentration
  
• particle size
  
• use of a catalyst 

For the students who want to do white:

OneNote: Workbook 5.4

Do exercises 1 - 24.

Blue: Reaction profiles

Exothermic reactions transfer energy to the surroundings and the temperature of the surroundings increases. Endothermic reactions take in energy and the temperature of the surroundings decreases.

This can be show using a reaction profile: 
 

The reaction profile shows the total amount of energy inside the products and the reactants. (So not in the surroundings!) 

Which of these images shows an exothermic reaction?

Homework blue:

OneNote: workbook 5.4

White exercises: 5-21

Blue exercises:  1-7