Paper 2 (wrongs)

Question 1

what is wrong with lead

Answer 1

lead is toxic/poisonous so is harmful

Question 2

Suggest one reason why solders B and C have different melting points.

Answer 2

the proportions of metals are different

Question 3

Copper is extracted from low-grade ores by phytomining. Describe how copper is extracted from low-grade ores by phytomining.

Answer 3

1. grow plants (on land containing copper ores)
2. plants are burnt (to produce ash)
3. ash dissolved in acid (to produce a solution of a copper
   compound)
4. electrolysis of solution (containing a copper compound)

Question 4

Phytomining has not been widely used to extract copper. Suggest two reasons why.

Answer 4

• high grade ores are still available
• there is not enough land
• it takes a long time
• new technology

Question 5

Describe the conditions used to produce ethene from large hydrocarbon molecules.

Answer 5

heat to a high temperature
pass over steam/catalyst

Question 6

Butanol can be produced from sugar solution by adding bacteria. Sugar solution is broken down in similar ways by bacteria and by yeast. Suggest the reaction conditions needed to produce butanol from sugar solution by adding bacteria.

Answer 6

warm and anaerobic conditions (37 degrees?)

Question 7

test for sulfates

Answer 7

add hcl to remove impurities (carbonate, sulfite) , then add barium chloride
produces white precipitate

Question 8

Describe how sewage is treated to remove organic matter.

Answer 8

screening
or
grit removal
sedimentation (to produce
sewage sludge and effluent)
anaerobic digestion of (solid
sewage) sludge
aerobic biological treatment of
(liquid) effluent

Question 9

A student predicted that heavy fuel oil is more viscous than kerosene. Justify the student’s prediction.

Answer 9

as molecular size increases
viscosity increases
(and) heavy fuel oil has larger
molecules (than kerosene)

Question 10

Natural gas is a fossil fuel. Describe how deposits of natural gas were formed.

Answer 10

Plankton died, covered by sediment, and in anaerobic conditions. they were compressed under extreme temperatures and high pressure

Question 11

Give the sources of the nitrogen and of the hydrogen used in the Haber process.

Answer 11

Natural gas (methane)

Question 12

Explain why these conditions are chosen for economical production of ammonia in the Haber process. You should include references to the rate of reaction and the yield

Answer 12

Temperature - more particles collide, faster ROR BUT the forward reaction is exothermic so raising the temperature would move equilibrium in the wrong direction so the yield would be smaller. SOOO the compromise is 450 degrees#
Pressure - Higher means more collisions so faster ROR and also means higher % yield but it is expensive and dangerous if too high so compromise is 200 atm
Catalysts - lower the activation energy so increase ROR

Question 13

Suggest why poly(butene) insulation must be removed from scrap copper wire before the copper is recycled.

Answer 13

otherwise the copper produced would be impure

Question 14

Suggest two reasons why recycling scrap copper is more sustainable than extracting copper from copper ores.

Answer 14

scrap copper requires less energy
recycling scrap copper produces less waste

Question 15

A solution can be added to copper sulfate solution to show the presence of copper(II) ions. Name the solution added. Give the result of the test.

Answer 15

Sodium hydroxide solution
blue precipitate
(testing for cations)

Question 16

What type of reaction takes place when hydrated cobalt chloride is heated?

Answer 16

Endothermic

Question 17

Fractions from crude oil can be processed to produce feedstock for the petrochemical industry. Which two are useful materials produced from this feedstock?

Answer 17

Detergents
Solvents

Question 18

what are the products of complete combustion

Answer 18

CO2 + H2O

Question 19

what is in NPK fertilisers

Answer 19

Nitrogen, Phosphorus, Potassium

Question 20

where does the nitrogen come from in NPK fertilisers (how to make Ammonium Nitrate)

Answer 20

first we get ammonia from the haber process then make nitric acid from the ammonia and react that again with ammonia to make ammonium nitrate

Question 21

explain how line spectroscopy works

Answer 21

a sample is placed in a flame and as the ions in the sample heat up, they transfer energy as light. this light passes through a spectroscope and produces a line spectrum specific to that ion

Question 22

is line spectroscopy good for identifying metal ions

Answer 22

a flame test would not be useful in identifying the metal ions in the mixture because different metal ions produce different colours. in a flame test, the colours would mix and mask each other

Question 23

properties of simple molecular substances

Answer 23

atoms within the molecules are held together by very strong covalent bonds but the forces of attraction between these molecules are very weak

Question 24

In the UK, potable (drinking) water is produced from different sources of fresh water. Explain how potable water is produced from fresh water.

Answer 24

• obtain fresh water from places such as rivers, streams, lakes
• pass through filter beds which removes insoluble solids
• sterilise with UV light to remove microbes

Question 25

Suggest the two processes this country could use to obtain most of its potable water.

Answer 25

• distillation
• reverse osmosis

Question 26

compare the reactions and structure of ethane and ethene

Answer 26

• both are hydrocarbons
• both contain two carbons in each molecule
• ethane contains 6 hydrogens but ethene contains 4.
• Both react with oxygen in complete combustion to produce water are carbon dioxide
• Both react with oxygen in incomplete combustion to produce water, carbon dioxide and carbon monoxide
• ethene reacts with bromine water but ethane doesn’t
• ethene can react with water (to produce ethanol)
• ethene is more reactive

Question 27

The green ink contains more than two compounds. Suggest one reason why only two spots are seen on Figure 2. chromatography

Answer 27

some of the compounds are colourless (in solution)
or
dyes / compounds have the same Rf values

Question 28

The manufacturers of the green ink always use the same proportions of yellow dye and blue dye. Suggest one reason why.

Answer 28

because the green ink is a formulation
or
So that the shade is the same

Question 29

The Rf value of a dye depends on:
* the solubility of the dye in the solvent
* the attraction of the dye to the paper. Which will definitely produce a smaller Rf value if the solvent and paper are both changed?
which is right - The dye is less soluble in the new solvent and more attracted to the new paper
The dye is more soluble in the new solvent and more attracted to the new paper

Answer 29

the dye is less soluble in the
new solvent and more attracted
to the new paper

Question 30

Explain why soot is formed when some fossil fuels are burned.

Answer 30

incomplete combustion because of insufficient oxygen

Question 31

Fossil fuels are burned in car engines. Explain how reducing the amount of sulfur in fossil fuels reduces the erosion of limestone.

Answer 31

sulfur reacts with oxygen to form sulfur dioxide. so less carbon dioxide is emitted . this means less acid rain so less limestone reacts with acid rain

Question 32

Oxides of nitrogen are atmospheric pollutants which are formed in car engines. Explain why oxides of nitrogen are formed in car engines.

Answer 32

(car engines work at) high temperatures (so in the engine) nitrogen (from air) reacts with oxygen (from air)
AT HIGH TEMPS NITROGEN REACTS WITH OXYGEN

Question 33

what is a weak and strong acid

Answer 33

Weak Acids are the acids that do not completely dissociate into their constituent ions when dissolved in solutions
Strong acids are acids that are completely dissociated in an aqueous solution.

Question 34

A student adds a solution of ethanoic acid to zinc carbonate in an open flask on a balance. Explain what happens to the mass of the flask and its contents during the reaction.

Answer 34

• the mass will decrease
• this is because when reacts with carbonate, produced CO2
• CO2 escapes and is released into atmosphere

Question 35

Give the name of the ester produced when ethanoic acid reacts with ethanol.

Answer 35

ethyl ethanoate

Question 36

Glucose is produced when algae photosynthesise. Name two naturally occurring polymers produced from glucose.

Answer 36

starch
cellulose

Question 37

Glycine reacts by condensation polymerisation to produce a polypeptide and one other substance. Name the other substance produced.

Answer 37

water

Question 38

Explain why a change in pressure does not affect the colour of the equilibrium mixture. (they are liquids)

Answer 38

equilibrium does not change because there are no gases. pressure cannot in liquids