Energy changes are an important part of chemical reactions. The interaction of particles often involves transfers of energy due to the breaking and formation of bonds. Reactions in which energy is released to the surroundings are exothermic reactions, while those that take in thermal energy are endothermic.

Task 2b: Make notes that:

• Describe the signs of a chemical reaction.

• Describe what happens in a chemical reaction, using a diagram to help.

• Explain how energy is used and released in a reaction

Task 3c: Make notes that:

• Define an exothermic reaction

• Define an endothermic reaction

• Explain the difference between an exothermic and endothermic reaction in terms of energy and temperature change in the surroundings

Task 3e: Complete the exam questions and mark your answers

Task 4b: Make notes that:

• Give instructions for drawing an endothermic reaction profile, including an example

• Give instructions for drawing an exothermic reaction profile, including an example

• Compare the reaction profiles for endothermic and exothermic reactions

• Define activation energy

• Draw and label the activation energy on a reaction profile

Task 4c: Complete the progress quiz

Task 5c: Make notes that:

• Define catalyst.

• Draw a reaction profile to show a reaction with a catalyst and a reaction without a catalyst (use slide 7 to help).

• Use the data on slide 22 to:

  • Name the most effective catalyst and explain your answer.

  • Name the least effective catalyst and explain your answer.

Task 7: - Complete the quiz to make sure you understand this unit.