Chemical Changes

Question 1

Combustion

Answer 1

Burning - a fuel reacts with oxygen to release energy

Question 2

3 things needed for combustion

Answer 2

Fuel. Heating and oxygen

Question 3

Combustion equation

Answer 3

Hydrocarbon + oxygen = carbon dioxide + water + energy

Question 4

Oxidation

Answer 4

When a substance reacts and combines with oxygen

Question 5

Thermal decomposition

Answer 5

When a substance breaks down into at least 2 other substances when heated

Question 6

Exothermic reaction

Answer 6

A reaction that transfers energy to the surroundings

Question 7

Example of an exothermic reaction

Answer 7

Combustion

Question 8

Endothermic reaction

Answer 8

A reaction that takes in heat from the surroundings

Question 9

Example of an endothermic reaction

Answer 9

Thermal decomposition

Question 10

Catalyst

Answer 10

A substance which speeds up a chemical reaction without being changed or used up in the reaction itself

Question 11

Advantage of catalysts

Answer 11

Increase speed and efficiency of the reaction
Can be reused

Question 12

Disadvantages of catalysts

Answer 12

Can be poisoned by impurities so they need to be cleaned