Chemistry: Classifying materials (6abcdefgh)

Question 1

What three properties could be used to identify an unknown substance?

Answer 1

Melting point, boiling point and density.

Question 2

What is the melting point of water?

Answer 2

0^oC

Question 3

What is the boiling point of water?

Answer 3

100^oC

Question 4

Does air have any mass?

Answer 4

Yes, it contains particles.

Question 5

What is an atom?

Answer 5

The basic building block of all materials, it is the smallest piece of an element.

Question 6

What is a molecule?

Answer 6

Two or more atoms joined together, it doesn’t matter if the atoms are the same or different. (e.g. Oxygen goes around in twos so exists as oxygen molecules rather than as atoms)

Question 7

What is a compound?

Answer 7

Molecules containing two or more different atoms.

Question 8

What state of matter would be represented by this diagram?

Answer 8

Solid

Question 9

Which state of matter has strong forces of attraction beween the particles so that they stay in a fixed position and a regular arrangement.

Answer 9

Solids

Question 10

Which state of matter has a fixed definite shape and volume?

Answer 10

Solids

Question 11

What happens when the particles in a solid are heated?

Answer 11

They vibrate more and therefore expand slightly until the point where they melt.

Question 12

In which state of matter are the particles free to move past each other, but tend to stay touching?

Answer 12

Liquids

Question 13

In which two states are the particles constantly moving around in random motion?

Answer 13

Gases and liquids

Question 14

Which state has no forces of attraction between the particles meaning that they are free to move?

Answer 14

Gases

Question 15

Which state of matter does not keep a definite shape or volume and will fill any container?

Answer 15

Gases

Question 16

When a gas is heated what happens?

Answer 16

It expands slightly or its pressure increases.

Question 17

Diffusion is the movement of particles from where there are lots of them (high concentration) to where there is few of them (low concentration). What states can this happen in, and why?

Answer 17

Gas and liquid, as the particles are able to move.

Question 18

What is an element?

Answer 18

A substance containing only one type of atom.

Question 19

What does the periodic table show?

Answer 19

All the known elements.

Question 20

How are elements arranged in the periodic table?

Answer 20

In groups (columns) of elements with similar properties.

Question 21

What are the symbols for oxygen, magnesium and copper?

Answer 21

O, Mg and Cu

Question 22

What are the chemical symbols for Nitrogen, Sulphur, Iron and Helium?

Answer 22

N, S, Fe and He

Question 23

What atoms would be found in water?

Answer 23

H₂O - two hydrogen atoms and one oxygen atom

Question 24

What is an electrical conductor?

Answer 24

A material which allows electricity to pass through it, e.g. copper and graphite.

Question 25

What is a thermal insulator?

Answer 25

A material that does not allow heat energy to pass through it. E.g. wood, plastic etc

Question 26

What metals are magnetic?

Answer 26

Iron, cobalt and nickel. Steel is also magnetic as it is an alloy of iron.

Question 27

When a metal reacts with oxgen what does it produce?

Answer 27

A metal oxide or hydroxide. These are both basic (opposite of acidic) and if they dissolve will make an alkali solution.

Question 28

Non metal oxides are…

Answer 28

acidic

Question 29

The properties of a compound often differ completely from those of the atoms that make them up. Give an example of this.

Answer 29

Water (liquid) is very different to the hydrogen (gas) and oxygen (gas) that make it up.

Iron sulphide (Iron and Sulphur) is another example.

Question 30

What chemical has the formula NaCl?

Answer 30

Sodium Chloride (common salt)

Question 31

What chemical has the formula CaCO₃?

Answer 31

Calcium carbonate (as found in chalk, limestone and marble)

Question 32

Aluminium + Iodine –>

Answer 32

Aluminium iodide

Question 33

Copper + sulphur –>

Answer 33

Copper sulphide

Question 34

What percentage of the air is made up of nitrogen?

Answer 34

78%

Question 35

What percentage of the air is made up of oxygen?

Answer 35

Approximately 21%

Question 36

Other than oxygen and nitrogen what other gases make up air?

Answer 36

Argon (approx 1%) and carbon dioxide (0.03%)

Question 37

What is a mixture?

Answer 37

Something containing different molecules that are not chemically combined. E.g. air, sea water

Question 38

Is it easy to separate a mixture?

Answer 38

Yes normally, because the parts of it are not joined together.

Question 39

What is a solute?

Answer 39

The substance which is dissolved to make a solution (e.g. sugar in tea)

Question 40

What is a solvent?

Answer 40

The substance (normally liquid) into which things dissolve. E.g. the water in a cup of tea.

Question 41

What is a solution?

Answer 41

what is formed when a solute dissolves in a solvent. e.g a sugary cup of tea.

Question 42

Alcohol dissolves in water, how could they be separated?

Answer 42

Distillation as they have different boiling points.

Question 43

What is distillation?

Answer 43

A process which involves evaporation and then condensation.

Question 44

How can coloured solutes (pigments) be separated from a mixture?

Answer 44

Chromatography.

Question 45

In a chromatagram which solute travels the furthest?

Answer 45

The most soluble.

Question 46

In this chromatagram:

a) which ink was a mixture?
b) which ink was least soluble?

Answer 46

a) Black (more than one dot above it)
b) red - it moved less far than the others.

Question 47

If I had a suspension of chalk (insoluble) in water, how could I seperate them?

Answer 47

filtration

Question 48

When filtering a substance what is the residue and what is the filtrate? Use filtration of chalk water to explain.

Answer 48

Residue - what gets stuck in the filter paper ( chalk powder)

Filtrate - the liquid that passes through the filter paper (clean water)