Types of Chemical Reaction Pt1

Question 1

What is an exothermic reaction?

Answer 1

Gives out heat

Question 2

What is an endothermic reaction?

Answer 2

Takes in heat.

Question 3

Give 3 examples of exothermic reactions

Answer 3

Combustion
Neutralisation
Displacement

Question 4

Give three examples of endothermic reactions

Answer 4

Cracking
Photosynthesis
Thermal Decomposition

Question 5

Give four indications that a chemical reaction has taken place.

Answer 5

Temperature change
Colour change
Precipitate
Gas production

Question 6

Define the term neutralisation reaction

Answer 6

When an acid and alkali react together the hydrogen and hydroxide ions form water.

H+ + OH- –> H2O

Question 7

Define the term combustion

Answer 7

Reaction of a fuel with oxygen to produce at least one oxide and releases energy.

Fuel + oxygen —> carbon dioxide + water + heat

Question 8

Define the term displacement reaction

Answer 8

When a more reactive element will remove a less reactive element from its compound

Zinc + copper sulfate –> zinc sulfate + copper
Chlorine + potassium bromide –> potassium chloride + bromine

Question 9

Define the term thermal decomposition

Answer 9

Breaking down using heat

Copper carbonate –> copper oxide + carbon dioxide

Green –> black

Question 10

Define the term cracking

Answer 10

Breaking long chained hydrocarbon compounds into shorter chain

Question 11

Bond breaking is endothermic or exothermic

Answer 11

Endothermic

Question 12

Bond making is endothermic or exothermic

Answer 12

Exothermic

Question 13

Consider the reaction between hydrogen and chlorine
H2 + Cl2 –> 2HCl
Explain in terms of bond breaking and bond making why this is an exothermic process.

Answer 13

Energy is required to break bonds in H2 and Cl2
Energy is released when new bonds are made in HCl
More energy is given out than taken in so the reaction is exothermic

Question 14

Give an equation for the thermal decomposition of limestone to form quick lime

Answer 14

Calcium carbonate –> calcium oxide + carbon dioxide

Question 15

Give a use for limestone

Answer 15

Blast furnace, the extraction of iron ore.
The calcium carbonate thermally decomposes and the calcium oxide combines with acidic impurities forming slag (calcium silicate)
CaCO3 —-> CaO + CO2
CaO + SiO2 –> CaSiO3

Question 16

Give two uses for quick lime CaO

Answer 16

To mix with water making limewater
CaO + H2O –> Ca(OH)2
To make plaster

Question 17

Give three advantages of limestone quarrying

Answer 17

Provides jobs
Boosts economy
Provides a raw material for blast furnace and neutralising soil

Question 18

Give three disadvantages of limestone quarrying

Answer 18

Eye sore
Ruins animal’s habitats
Noise or dust pollution

Question 19

In a chemical reaction if more heat is given out than taken in in will be

Answer 19

Exothermic

Question 20

In a chemical reaction if less heat is given out than taken in it will be.

Answer 20

Endothermic