Paper 2 Questions

Question 1

Explain why nanoparticles may have properties that are different from the properties in bulk. [2]

Answer 1

• Nanoparticles have a high surface to volume ratio (1 mark).
• Smaller quantities are therefore are needed for them to more effective than materials with normal particles sizes (1 mark).

Question 2

What are the first four members of the alcohol homologous series? [4]

Answer 2

1. Methanol (1 mark)
2. Ethanol (1 mark)
3. Propanol (1 mark)
4. Butanol (1 mark)

Question 3

How are aqueous solutions of ethanol produced? [2]

Answer 3

sugar solutions are fermented (1 mark) using yeast (1 mark)

Question 4

When carboxylic acids react with alcohols, what do they produce? [2]

Answer 4

ester (1 mark) and water (1 mark)

Question 5

What are alkenes used for? [1]

Answer 5

they are used to produce polymers/ are the starting material for other chemicals . [1]

Question 6

Alkenes along with alkanes can be produced from cracking. How do we test for alkenes and what do we see? [2]

Answer 6

• tested with bromine water (1 mark)
• it will turn bromine water colourless (1 mark).

Question 7

Define condensation polymerisation [3]

Answer 7

• Condensation polymerisation involves monomers with two functional groups (1 mark)
• When these monomers react they join together (1 mark) usually losing small molecules,
• so are called condensation polymerisation reactions (1 mark).

Question 8

What must the two monomers have in common for the condensation polymerisation reaction to
occur? [1]

Answer 8

The same functional group [1]

Question 9

Describe how crude oil is separated into fractions [4]

Answer 9

• Heat the crude oil; [1 mark]
• (The hydrocarbons) vapourise/evaporate/boil; [1 mark]
• The column is hotter at the bottom and cooler at the top; [1 mark]
• Vapours/fractions condense; [1 mark]
• At their boiling points/ levels; [1 mark]

Question 10

Compare the properties of gasoline and fuel oil [4]

Answer 10

Similarities:
Any two from:
- Both fractions are made up of alkanes; [1 mark]
- Both fractions consist of hydrocarbons; [1 mark]
- Fractions only contain single bonds/are saturated; [1 mark]
Differences:
Any two from:
- Fuel oil is less flammable; [1 mark]
- Fuel oil is more viscous; [1 mark]
- Fuel oil has a higher boiling point; [1 mark]
- Fuel oil is a longer hydrocarbon; [1 mark]

Question 11

Describe two effects of nitrogen oxides being released into the atmosphere [2]

Answer 11

• Acid rain; [1 mark]
• Erosion of limestone; [1 mark]
• Respiratory/breathing problems; [1 mark]
• Kills aquatic/plant life; [1 mark]

Question 12

Hydrogen fuel cells are commonly considered to be carbon neutral by the general public because they do not release any carbon dioxide or
other greenhouse gases when they are used. This is not technically correct.
Suggest why hydrogen fuel cells cannot be classed as carbon neutral. [1]

Answer 12

Carbon dioxide / CO2 is released when the fuel cell is manufactured / made
OR
Carbon dioxide / CO2 is released when the raw materials to make the fuel cell are transported to the factory / assembly plant
OR
Carbon dioxide / CO2 is released when hydrogen is produced; [1 mark]

Question 13

The Earth’s earliest rocks contained iron sulfide and no iron oxide. Later, the rocks contained iron sulfide as well as iron oxide.
Explain what happened to allow this change to occur [2]

Answer 13

Oxygen levels increased; [1 mark]
So the iron was oxidised / the oxygen reacts with the iron; [1 mark]

Question 14

The amount of oxygen in the Earth’s atmosphere has increased since its early atmosphere was formed.
Explain what caused this change [2]

Answer 14

This change has been caused by:

• Plants (growing / evolving); [1 mark]
• Photosynthesis occurs ; [1 mark]

Question 15

Nanoparticles of titanium(IV) oxide are used in some sunscreens.
Describe a reason why nanoparticles of titanium(IV) oxide are used in some sunscreens. [2]

Answer 15

A description to include the following points
- can {absorb/block} UV light from the skin (1)
- therefore can prevent sunburn (1)
OR
- particles are very small (1)
- (therefore) appear invisible / cannot be seen on the skin (1)

Question 16

The actual percentage of carbon dioxide in the Earth’s atmosphere today varies.
Explain two factors that cause the percentage of carbon dioxide in today’s atmosphere to vary. [4]

Answer 16

• combustion/ burning of fossil fuels (1)
• {increases/ gives out} carbon dioxide (1)
• respiration (1)
• increases carbon dioxide (1)
• increases in sea temperature (1)
• release of (dissolved) carbon dioxide (1)
• photosynthesis (1)
• {absorbs/ takes in/ reduces} carbon dioxide (1)
• carbon dioxide (dissolves) into the sea (1)
• carbon dioxide decreases (1)
• volcanic emissions (1)
• releases carbon dioxide (1)
• deforestation means less photosynthesis (1)
• carbon dioxide increases (1)
• use of alternative energy/ electric cars (1)
• less carbon dioxide release (1)

Question 17

The reaction between calcium carbonate and dilute hydrochloric acid is exothermic.
Explain, in terms of bond breaking and bond making, why some reactions are exothermic. [3]

Answer 17

• breaking bonds {needs energy/ endothermic} (1)
• making bonds {releases energy/ exothermic} (1)
• more energy is given out than is taken in (1)

Question 18

The experiments were repeated at a higher temperature.
The rate of reaction for each experiment increased.
Explain, in terms of particles, why the rate of reaction increased when the temperature was increased. [2]

Answer 18

• particles have more energy (1)
• so (particles) move faster (1)
• (so) there are more frequent collisions between particles (1)
• higher proportion of collisions have at least
  the activation energy to react when particles collide (1)

Question 19

Describe the test to show the gas is ammonia [2]

Answer 19

test gas with moist (red) litmus paper (1)
* turns blue (1)

Question 20

Sodium hydroxide solution is also used to distinguish between iron(II) ions, Fe2+ and iron(III) ions, Fe3+, in solution.
You are given a solution containing iron(II) ions and another solution containing iron(III) ions.
Describe what is seen when sodium hydroxide solution is added to each of these solutions. [2]

Answer 20

• iron(II) – green/pale green/greygreen and precipitate /solid (1)
• iron(III) – red-brown/brown and precipitate /solid (1)

Question 21

A teacher conducts a flame test to identify the metal ions in some unknown solids.
step 1 dip a flame test wire into hydrochloric acid
step 2dip the flame test wire into the unknown solid
step 3 hold the flame test wire above a Bunsen burner flame
This method did not work well.
Explain an improvement that needs to be made to step 3 to enable a bright flame colour to be produced. [2]

Answer 21

• hold the wire in the flame / at the tip of the (blue) cone (1)
• (as) it is hotter (1)

Question 22

State a problem with recycling polymers [1]

Answer 22

• need to sort polymers into different types
• polymers often need to be separated from other polymers
• takes time to sort by hand
• containers may need to be washed before recycling
• difficult to break down into their monomers
• some not recyclable
• requires a lot of energy

Question 23

Compound Z is an acid and turns litmus and universal indicator papers red.
Compound Z also shows other acidic properties.
Devise an experiment that would show another acidic property of compound Z. [2]

Answer 23

• add a piece of magnesium ribbon (1)
• bubbles of gas form (1)
• add a (metal) carbonate (1)
• bubbles of gas form (1)
• add a metal oxide and warm (1)
• metal oxide reacts to form a solution (1)
• measure pH (1)
• pH less than 7 (1)
• add an alkali (1)
• a neutral solution produced (1)

Question 24

Nanoparticles have many uses.
Some scientists are concerned about the possible risks of using nanoparticles.
Give one risk of using nanoparticles [1]

Answer 24

Damages cells
OR
Cause heart problems
OR
Get into the bloodstream / cells
OR
Catalyse harmful reactions
OR
Are harmful to aquatic life; [1 mark]