Topic 5 - Chemical Reactions

Question 1

What type of process is bond breaking and what process is making bonds?

Answer 1

Breaking bonds = Endothermic

Making bonds = Exothermic

Question 2

In an Endothermic process what happens to energy?

Answer 2

Energy is supplied to break the bonds

Question 3

In an Exothermic process what happens to the energy?

Answer 3

Energy is given out when new bonds are formed

Question 4

What is an Exothermic reaction?

Answer 4

Is one which overall gives out energy to the surroundings in the form of heat, shown by a rise in temperature.

Question 5

What is an Endothermic reaction?

Answer 5

Is one which overall takes in energy from the surroundings in the form of heat, shown by a fall in temperature.

Question 6

What does a exothermic reaction graph look like?

Answer 6

• The reactants are at a higher energy than the products

Question 7

What does an endothermic reaction graph look like?

Answer 7

• The reactants are at a lower energy than the products

Question 8

What is an example of an exothermic reaction?

Answer 8

• Combustion (Burning fuels)

Question 9

What is an example of endothermic reaction?

Answer 9

• Photosynthesis

Question 10

What four things does a rate of reaction depend on?

Answer 10

1. Temperature
2. Concentraion (Or pressure for gases)
3. Catalyst
4. Surface Area

Question 11

What is a catalyst?

Answer 11

A catalyst is a substance which changes the speed of a reaction, without being used yp in the reaction.

Question 12

In car exhausts how are catalysts in catalytic converters used?

Answer 12

• High surface area to increase rate of reaction
• Work best at high temperatures
• It turns carbon monoxide, unburnt fuel and oxygen into carbon dioxide and water

Question 13

By increasing either temperature, concentration, surface area or adding a catalyst what happens to the particles?

Answer 13

• They’re going to have more frequent successful collisions