C1.2 - R* Chemical equations

Question 1

What do chemical equations show?

Answer 1

Chemical equations show the:
1. Reactants
2. Products
in a reaction

Question 2

What happens in chemical reactions?

Answer 2

In chemical reactions, the atoms get rearranged

Question 3

Reactant

Answer 3

A reactant is a substance we start with before a chemical reaction takes place

Question 4

Product

Answer 4

A product is a substance made as a result of a chemical reaction

Question 5

Word equation

Answer 5

A word equation is a way of describing what happens in a chemical reaction by showing the:

1. Names of all the reactants
2. Products they form

Question 6

Balanced symbol equation

Answer 6

A balanced symbol equation is a symbol equation in which there are equal numbers of each type of atom on either side of the equation

Question 7

What can atoms not be in a chemical reaction?

Answer 7

In a chemical reaction, atoms can not be:
1. Created
Or,
2. Destroyed

Question 8

Law of conservation of mass

Answer 8

The Law of conservation of mass is that the total mass of the products formed in a reaction is equal to the total mass of the reactants

Question 9

In reactions involving gases, when the reactions are carried out in open containers (such as test tubes and conical flasks), what law can appear to be broken?

Answer 9

In reactions involving gases, when the reactions are carried out in open containers (such as:
1. Test tubes
2. Conical flasks
), the Law of conservation of mass can appear to broken

Question 10

Aqueous solution

Answer 10

An aqueous solution is the mixture made by adding a soluble substance to water

Question 11

What are formulas and equations used to do?

Answer 11

1. Formulas
2. Equations
   are used to show what is happening to the substances involved in chemical reactions

Question 12

Just as elements can be represented by symbols, how can compounds be represented?

Answer 12

Just as elements can be represented by symbols, compounds can be represented by (chemical) formulas

Question 13

Chemical formula of carbon dioxide

Answer 13

The chemical formula of carbon dioxide is CO2

Question 14

Chemical formula of ammonia

Answer 14

The chemical formula of ammonia is NH3

Question 15

Chemical formula of water

Answer 15

The chemical formula of water is H2O

Question 16

Chemical formula of sodium chloride

Answer 16

The chemical formula of sodium chloride is NaCl

Question 17

Chemical formula of carbon monoxide

Answer 17

The chemical formula of carbon monoxide is CO

Question 18

Chemical formula of hydrochloric acid

Answer 18

The chemical formula of hydrochloric acid is HCl

Question 19

Chemical formula of calcium chloride

Answer 19

The chemical formula of calcium chloride is CaCl2

Question 20

Chemical formula of sodium carbonate

Answer 20

The chemical formula of sodium carbonate is Na2CO3

Question 21

Chemical formula of sulfuric acid

Answer 21

The chemical formula of sulfuric acid is H2SO4

Question 22

How are chemical changes shown?

Answer 22

Chemical changes are shown using chemical equations

Question 23

One way to show a chemical reaction

Answer 23

One way to show a chemical reaction is to write a word equation

Question 24

One way to show a chemical reaction is to write a word equation.
Describe word equations

Answer 24

Word equations:
1. Are not as quick as using chemical symbols
2. You can’t tell straight away what’s happened to each of the atoms
,but it is very easy

Question 25

What do symbol equations need to be?

Answer 25

Symbol equations need to be balanced

Question 26

Symbol equations need to be balanced. There must always be the same number of atoms on both sides. How do you balance an equation?

Answer 26

You balance an equation by putting numbers in front of the formulas where needed

Question 27

What does a piece of copper do, when heated in air?

Answer 27

When heated in air, a piece of copper increases in mass

Question 28

Why does a piece of copper increase in mass when heated in air?

Answer 28

A piece of copper increases in mass when heated in air, because the apparent extra mass comes from the oxygen gas that the copper reacts with to make copper oxide

Question 29

If you weigh a sample of calcium carbonate before you heat it, then weigh it again after heating, what will it appear to do?

Answer 29

If you weigh a sample of calcium carbonate before you heat it, then weigh it again after heating, it will appear to lose mass

Question 30

Symbol equations need to be balanced. | There must always be what on both sides?

Answer 30

There must always be the same number of atoms on both sides

Question 31

If you weigh a sample of calcium carbonate before you heat it, then weigh it again after heating, what will it appear to do?

Answer 31

If you weigh a sample of calcium carbonate before you heat it, then weigh it again after heating, it will appear to lose mass

Question 32

If you weigh a sample of calcium carbonate before you heat it, then weigh it again after heating, why will it appear to lose mass?

Answer 32

If you weigh a sample of calcium carbonate before you heat it, then weigh it again after heating, it will appear to lose mass, because the carbon dioxide gas formed in the reaction will escape into the air