C5 - Chemicals in the Natural Environment

Question 1

What are the three most abundant elements in the world?

Answer 1

Oxygen, silicon and aluminium

Question 2

Covalent bonds

Answer 2

Bonds with shared elections

Question 3

Electrostatic attraction

Answer 3

When the positively charged nuclei are attracted to the negatively charged shared pair of electrons

Question 4

Why do simple molecular structures have low melting points?

Answer 4

Because they have weak intermolecular bonds

Question 5

What is the hydrosphere?

Answer 5

All of the water on Earth e.g. Oceans, seas, lakes and rivers

Question 6

What structure do ionic compounds form?

Answer 6

A crystal lattice

Question 7

Why do ionic compounds have high melting points?

Answer 7

Because they have very strong intermolecular forces and the ions have strong attractive forces

Question 8

Why do ionic compounds only conduct electricity when molten?

Answer 8

When molten or dissolved, ionic compound conduct electricity because the ions are free to move

Question 9

What colour precipitate does a Calcium ion form? And is it soluble?

Answer 9

White: insoluble in excess

Question 10

What colour precipitate does a Copper ion form? And is it soluble?

Answer 10

Light blue: insoluble in excess

Question 11

What colour precipitate does an Iron (II) ion form? And is it soluble?

Answer 11

Green: insoluble in excess

Question 12

What colour precipitate does an Iron (III) ion form? And is it soluble?

Answer 12

Red-brown: insoluble in excess

Question 13

What colour precipitate does a Zinc ion form? And is it soluble?

Answer 13

White: soluble in excess

Question 14

How do you test for a Carbonate ion? (2)

Answer 14

Add dilute acid and see if Bubbles (effervescence) occurs

Question 15

How do you test for a Sulphate ion? (4)

Answer 15

Add dilute acid then acidity with nitric acid then add barium chloride/ nitrate; see if a white precipitate forms

Question 16

How do you test for a Chloride ion? (4)

Answer 16

Add dilute acid then acidity with nitric acid then add silver nitrate; see if a white precipitate forms

Question 17

How do you test for an Iodide ion? (4)

Answer 17

Add dilute acid then acidity with nitric acid then add silver nitrate; see if a yellow precipitate forms

Question 18

How do you test for a Bromide ion?(4)

Answer 18

Add dilute acid then acidity with nitric acid then add silver nitrate; see if a cream precipitate forms

Question 19

What is the Lithosphere?

Answer 19

The rigid outer layer of the Earth, made up of the crust and upper mantle

Question 20

Ore

Answer 20

A rock containing a metal/ metal compound

Question 21

Name as many properties of metals as you can: (7)

Answer 21

Malleable, solid, strong/ hard, shiny, high melting/ boiling points, good conductor, free electrons to carry electrical current

Question 22

Alloy

Answer 22

A mixture of different metals

Question 23

What element is used to extract iron, zinc and copper?

Answer 23

Carbon

Question 24

What is a redox reaction?

Answer 24

A reaction where oxidation and reduction take place

Question 25

What is another name for aluminium ore?

Answer 25

Bauxite

Question 26

Give the four properties of aluminium?

Answer 26

Lightweight, flexible, strong and durable

Question 27

What are the conditions needed for aluminium electrolysis? (3)

Answer 27

955 degrees Celsius, 4.5V and 157,000 Amps

Question 28

Name as many properties of diamond as you can: (7)

Answer 28

- Expensive and rare - Giant covalent structure - Transparent - Used in drill tips & jewellery - Carbon atoms bonded to four others in tetrahedral pattern - Doesn't conduct electricity - Hard and strong

Question 29

Name as many properties of graphite as you can: (7)

Answer 29

- Cheap and common - Has delocalised electrons between the layers - Black - Used in pencil lead and as an electrode during electrolysis - Soft with weak bonds between layers - Conducts electricity - Carbon atoms bonded to three others in sheets

Question 30

Name as many properties of silica/ silicon dioxide as you can: (6)

Answer 30

- makes up most of the Earth's crust - Silicon atoms bonded to four oxygen atoms - Hard & strong - High melting and boiling points - Insoluble - Doesn't conduct electricity

Question 31

What is the equation to calculate the % of metal in a mineral?

Answer 31

% metal + total mass of metal atoms / gram formula mass X 100

Question 32

Electrolysis

Answer 32

Passing an electric current through an ionic compound when it is molten/ dissolved in water

Question 33

Why is Aluminium extracted using electrolysis?

Answer 33

It is very reactive so it's oxide cannot be reduced by carbon

Question 34

Why do metals form at the cathode and non metals at the anode?

Answer 34

Metals form positive ions and non metals form negative ones

Question 35

Why are metals malleable?

Answer 35

All the atoms are the same size and care roll over each other while keeping the bonds

Question 36

Give three examples of poisonous metals

Answer 36

Lead, mercury and cadmium

Question 37

Why is sulphur dioxide harmful to the environment?

Answer 37

It helps form acid rain which damages plants and fish

Question 38

What is lithium used for?

Answer 38

Batteries

Question 39

Why don't we use lead to make batteries anymore?

Answer 39

Lead is toxic

Question 40

What do we use copper for?

Answer 40

Electrical wiring, pipes and building materials

Question 41

What substances are in dry air in what percentages?

Answer 41

Nitrogen - 78% Oxygen - 21% Carbon Dioxide - 0.04% Argon & other gases -