C2 - Exam Mistakes

Question 1

What type of compound is a metal oxide?

Answer 1

A base

allows ionic

Question 2

Which substance are used in electrolysis to form alumimium?

Answer 2

Cryolite and aluminium oxide (NOT BAUXITE)

Question 3

When making polymers from monomers, what decides the density of the polymer?

Answer 3

Temperature of the conditions of the reactions

Question 4

Give 2 reasons that instrumental methods are used to detect impurities in metals

Answer 4

Very accurate

Uses small samples

Question 5

In relative atomic mass, what is the mass of the element compared with?

Answer 5

Carbon-12

Question 6

How can a solid be obtained from its solution?

Answer 6

Water is evaporated off

Question 7

Why does increasing surface area increase the rate of reaction? 2 marks

Answer 7

More of reactant exposed to other reactant so more FREQUENT collisions

Question 7

What is the structure of a metal?

Answer 7

A giant lattice structure of many positive metal ions surrounded by a sea of delocalised electrons

Question 8

Describe how the structure of an alloy is different to the structure of a pure metal and explain why. 3 marks

Answer 8

An alloy is a metal which has different sizes of atoms

Because it is made of 2 or more different metals and different s have differently sized atoms

This means that alloys gave distorted layers

Question 9

Why is Nitinol used in dental braces?

Answer 9

It is a shape memory so it can return to its original shape

Question 10

Why are coins not made of pure copper?

Answer 10

Too soft

Question 11

Describe the structure and bonding of a named ionic compound. 4 marks

Answer 11

Giant lattice structure

Contains ions

Contains positive metal ions and negative non-metal ions

Bonded by electrostatic attractions

Question 12

In paper chromatography, what is the start line drawn with and why?

Answer 12

Pencil and ruler

Pencil used because it will not smudge or run

Question 13

Why do different compounds separate in gas chromatography?

Answer 13

DIFFERENT SUBSTANCES travel at different speeds

Question 14

What do you have to say in questions about factors affecting rate of reaction?

Answer 14

More FREQUENT collisions

Question 15

Why is it concluded that group 1 metals are not suitable for reacting with and acid? 2 marks

Answer 15

Group 1 metals are very reactive

So the reaction is too violent and therefore dangerous

Question 16

Give 4 reasons that the actual yield is usually lower than the maximum theoretical yield

Answer 16

Reaction is reversible

Impure reactants

Some of the reactants may react in different ways than expected and produce unwanted products

Some reactants or products lost during reaction

Question 17

Why are carbon nanotubes used as lubricants? 2 marks

Answer 17

Nanotubes can slide over each other

Because no COVALENT bonds between the molecules

Question 18

Describe the structure and bonding in diamond. 4 marks

Answer 18

Giant lattice structure (macro molecular)

Strong bonds between carbon atoms

That are covalent

Each carbon atoms forms 4 bonds to other carbon atoms

Question 19

Describe the structure and bonding in a thermosoftening polymer and explain why they melt when heated. 4 marks

Answer 19

Large chain molecules

With intermolecular forces between chains

That are weak

Meaning they are easily overcome when heated

Question 20

Write the ionic equation for a neutralisation of hydroxide

Answer 20

H+ + OH- –> H^2O

Question 21

Suggest why the mass of crystals formed was less than the student has calculated

Answer 21

Because of an incomplete reaction

DON’T SAY REVERSIBLE REACTION

Question 22

300J are taken in when substance A forms substance B. What is energy change when B forms A. 2 marks

Answer 22

300J

Given out by the reaction

Question 23

What do you have to do in empirical formula questions?

Answer 23

Calculate the ratio and then write the compound as the answer

Example: carbon to nitrogen = 3:1

So the answer is C^3N

Question 24

What information does the molecular ion peak give about the molecule?

Answer 24

Relative MOLECULAR mass

Question 25

Scientists can’t answer “should we use gas instead of coal”. Give 2 reasons why

Answer 25

Determined by other people’s opinions too

Can’t be determined by experiments

Question 26

Explain why silicon dioxide is suitable for a furnace lining. 4 marks

Answer 26

Giant covalent structure

So only held together by strong covalent bonds

The strength of bonds means a high temperature is needed to break them

So high melting point so won’t melt because of temperatures of furnace

Question 27

Explain why copper is a good conductor of electricity. 2 marks

Answer 27

Copper has delocalised electrons

Which can move through the metal

Question 28

Why was hydrogen formed at the electrode instead of potassium. 2 marks

Answer 28

Both are positive ions

Potassium is more reactive than hydrogen

Question 29

Explain why carbon dioxide is a gas at low temperature. 3 marks

Answer 29

Simple covalent substances

Held together by weak intermolecular forces

Small amount of ENERGY to overcome forces so low temperature to overcome them

Question 30

Why would adding other substances to silicon dioxide to make glass make it melt at lower temperatures?

Answer 30

Weaker bonds

Question 31

Explain why iodine has a low melting point. 3 marks

Answer 31

Simple molecules

Held together by weak intermolecular forces

Easily overcome by low temperatures

Question 32

Explain why iodine doesn’t conduct electricity. 2 marks

Answer 32

No delocalised electrons or ions

So cannot carry CHARGE