Energy Changes

Question 1

What type of reaction is bond breaking

Answer 1

• endothermic as it requires energy

Question 2

What type of reaction is bond making

Answer 2

• exothermic as it releases energy

Question 3

Describe energy and bonding in exothermic reactions

Answer 3

• the energy released by forming bond is greater than the energy used to break them

Question 4

Describe energy and bonding in endothermic reactions

Answer 4

• the energy needed to break bonds is greater than the energy released by forming them

Question 5

What is activation energy

Answer 5

The minimum amount of energy needed for a chemical reaction to take place

Question 6

Reaction profile of an exothermic reaction

Answer 6

https://drive.google.com/file/d/13TSx7pgnf7DVCT_Plf67QNIvlYV9jshP/view?usp=drivesdk

• the reactants are at a higher energy than the products
• the difference in height between the reactants and products is the overall energy change
• the distance from the reactants to the peak of the graph is the energy needed to break the bonds (activation energy)
• the greater the activation energy, the more energy needed to start the reaction

Question 7

Reaction profile of an endothermic reaction

Answer 7

https://drive.google.com/file/d/12AXpkgIT3G1Gzy_JnifFNTnVYyuPf2Aq/view?usp=drivesdk

• the reactants are at a lower energy than the products
• the difference in the height between the reactants and products is the overall energy change
• the distance from the reactants to the peak of the graph is the activation energy
  (Activation energy is higher for endothermic reaction profiles)

Question 8

What are endothermic reactions

Answer 8

Reactions that take in energy from the surroundings

Question 9

What are exothermic reactions

Answer 9

Reactions that release energy to the surroundings

Question 10

Reactants have…

Answer 10

Positive bond energies, as breaking the bonds between the reactants takes in energy

Question 11

Products have…

Answer 11

Negative bond energies, as making the bonds in the products releases energy

Question 12

Exothermic reactions always have…

Answer 12

Negative bond energies, as the energy released to make the product is more than the energy takes in to break the reactants

Question 13

Endothermic reactions always have…

Answer 13

Positive bond energies, more energy is taken in to break the bonds between the reactants than released when forming the products

Question 14

Bond energy equation

Answer 14

Energy used to break reactants - energy released to make products

Question 15

Bond energy calculation question with working out

Answer 15

https://drive.google.com/file/d/14AmJQkko4CzVuAsbA9rmLWAWgNKsclOG/view?usp=drivesdk