Chemical reactions

Question 1

What are the substances that you start with in a chemical reaction called?

Answer 1

Reactants

Question 2

What are the substances that you finish with in a chemical reaction called?

Answer 2

Products

Question 3

In a word equation, where are the reactants located?

Answer 3

On the left

Question 4

In a word equation, where are the products located?

Answer 4

On the right

Question 5

What symbol is used to represent the reaction from reactants to products?

Answer 5

➞

Question 6

Write the balanced symbol equation for the reaction of copper and oxygen to form copper oxide.

Answer 6

2Cu + O2 ➞ 2CuO

Question 7

What does a balanced symbol equation show?

Answer 7

• The formula of each substance in the reaction
• How the atoms are rearranged
• The relative number of atoms of each substance

Question 8

What are some signs that a chemical reaction is occurring?

Answer 8

• Flames or sparks
• A smell
• Fizzing or a bang
• Change in temperature of the reaction mixture

Question 9

What is a catalyst?

Answer 9

A substance that speeds up a reaction without being used up

Question 10

Are chemical reactions normally reversible?

Answer 10

No

Question 11

What does a chemical reaction involve?

Answer 11

An energy transfer to or from the surroundings

Question 12

Define a decomposition reaction.

Answer 12

A reaction where a substance breaks down into simpler substances

Question 13

What is thermal decomposition?

Answer 13

A decomposition reaction that requires heat

Question 14

What is oxidation?

Answer 14

When substances react with oxygen

Question 15

What type of reaction is combustion?

Answer 15

A type of oxidation reaction where a fuel reacts with oxygen

Question 16

What are fossil fuels?

Answer 16

Non-renewable energy sources formed over millions of years

Question 17

What do fossil fuels produce when combusted?

Answer 17

Carbon dioxide and water

Question 18

Why is the combustion of fossil fuels harmful to the environment?

Answer 18

It releases carbon dioxide, contributing to climate change

Question 19

What is the product of burning hydrogen?

Answer 19

Water

Question 20

What is the temperature change in an endothermic reaction?

Answer 20

Decreases

Question 21

What type of reaction is thermal decomposition?

Answer 21

Endothermic

Question 22

What is the temperature change in an exothermic reaction?

Answer 22

Increases

Question 23

What type of reaction is combustion?

Answer 23

Exothermic

Question 24

What does the conservation of mass state?

Answer 24

Atoms are not created or destroyed; they are rearranged

Question 25

If the mass seems to increase in a reaction, what has happened?

Answer 25

Atoms have been added from a gas

Question 26

If the mass seems to decrease in a reaction, what has happened?

Answer 26

Atoms have formed a gas that has escaped

Question 27

Are changes of state chemical reactions?

Answer 27

No, they are physical changes

Question 28

What is a physical change?

Answer 28

A change where no new substances are made

Question 29

Fill in the blank: Water, ice, and steam are all made of molecules of the same substance (H2O) in different states, and the change from one state to another is _______.

Answer 29

Reversible

Question 30

List some key terms related to chemical reactions.

Answer 30

* Balanced symbol equation * Catalyst * Chemical reaction * Combustion * Conservation of mass * Decomposition * Endothermic * Exothermic * Word equation * Fossil fuel * Fuel * Non-renewable * Oxidation * Physical change * Product * Reactant * Reversible * Thermal decomposition