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Chemistry > Paper 2 (wrongs) > Flashcards

Paper 2 (wrongs) Flashcards

1
Q

what is wrong with lead

A

lead is toxic/poisonous so is harmful

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2
Q

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

A

the proportions of metals are different

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3
Q

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

A
  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)
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4
Q

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

A
  • high grade ores are still available
  • there is not enough land
  • it takes a long time
  • new technology
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5
Q

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

A

heat to a high temperature
pass over steam/catalyst

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6
Q

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.

A

warm and anaerobic conditions (37 degrees?)

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7
Q

test for sulfates

A

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

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8
Q

Describe how sewage is treated to remove organic matter.

A

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

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9
Q

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

A

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

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10
Q

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

A

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

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11
Q

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

A

Natural gas (methane)

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12
Q

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

A

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

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13
Q

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

A

otherwise the copper produced would be impure

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14
Q

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

A

scrap copper requires less energy
recycling scrap copper produces less waste

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15
Q

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.

A

Sodium hydroxide solution
blue precipitate
(testing for cations)

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16
Q

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

A

Endothermic

17
Q

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

A

Detergents
Solvents

18
Q

what are the products of complete combustion

A

CO2 + H2O

19
Q

what is in NPK fertilisers

A

Nitrogen, Phosphorus, Potassium

20
Q

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

A

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

21
Q

explain how line spectroscopy works

A

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

22
Q

is line spectroscopy good for identifying metal ions

A

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

23
Q

properties of simple molecular substances

A

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

24
Q

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

A
  • 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
25
Q

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

A
  • distillation
  • reverse osmosis
26
Q

compare the reactions and structure of ethane and ethene

A
  • 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
27
Q

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

A

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

28
Q

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

A

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

29
Q

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

A

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

30
Q

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

A

incomplete combustion because of insufficient oxygen

31
Q

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

A

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

32
Q

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

A

(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

33
Q

what is a weak and strong acid

A

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.

34
Q

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.

A
  • the mass will decrease
  • this is because when reacts with carbonate, produced CO2
  • CO2 escapes and is released into atmosphere
35
Q

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

A

ethyl ethanoate

36
Q

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

A

starch
cellulose

37
Q

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

A

water

38
Q

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

A

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

Chemistry (2 decks)

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