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chemistry > Chem Past Paper -2 > Flashcards

Chem Past Paper -2 Flashcards

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1
Q

What colour flame would sodium ions produce

A

Yellow

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2
Q

Name a metal ion that would produce a green flame

A

Copper

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3
Q

Some fireworks contain a mixture of metal ions. Why is it difficult to identify the metal ions from the colour of the flames

A

Colours are masked

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4
Q

Silver nitrate solution and dilute nitric acid are added t the solution. A cream precipitate forms. Which ion s shown to be present by the cream precipitate

A

Bromide

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5
Q

Descrive a test to show the presence ofsulfate ions in the solution. Give the result of the test if there are suklflate ions in the solution

A

add barium chloride (solution) add hydrochloric acid

white precipitate produced

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6
Q

What name is given to a useful prodcut such as methylated spirit

A

Formulation

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7
Q

Suggest why pyridine 9unpleasant spell0 and methyl violet (make mixture purple) to make methylated spirit

A

To deter consumption/drinking by people

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8
Q

Uses of methylated spirit

A

Fuel
Solvent
Antiseptic

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9
Q

Describe how ethanol is produced from sugar soluton

Give the name of this process

A

Fermentation
Add yeast
Anaerobic conditions
Warm

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10
Q

Name the gas produced when sodium is added to ethanol

A

Hydrogen

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11
Q

Methanol is used to prodcue methanoic acid, what tupe of subtance reacts with methanol to produce methanoic acid

A

Oxidising agent

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12
Q

Give the approximate temp used in haber process

A

450 C

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13
Q

Pressure used in haber process

A

200 atm

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14
Q

The mixture of gases from the reactor cools in the condensor

Suggest why ammonia condenses but the other gases do not

A

Ammonia has a higher bp

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15
Q

Why are scientist not certain about the percentage of each gas in the earth early atmosphere

A

Occured 4.6 bn years ago

Limited or no evidence

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16
Q

What is the problem in chromatography when line drawn in ink

A

Ink dissolves

Ink runs in solvent/water

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17
Q

What is the problem with water used in chromatography

A

Colour will not dissolve/move

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18
Q

Polyesters are produced when monomers join togetehr and lose a small molecule. Name this small molecule

A

Water

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19
Q

Why is a mixture of poly(propene) and wool is used to make carpets is more sustainable than using just one of the materials

A 
poly(propene) comes from a
non-renewable source
• poly(propene) requires a lot
of energy to make
• poly(propene) is not
biodegradable
• a wool carpet needs replacing more often
• wool requires the use of large areas of land (which could be used to grow food crops)
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20
Q

Explain how carbon monoxide is produced when petrol is bruned in car engine

A

Incomplete combustion

Insufficenient limited o2 supply

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21
Q

Suggest two reasons why maximum allowed percentage of carbonn monoxide has been decreased for newer cars

A

carbon monoxide toxic /
poisonous
• greater public concern / awareness about pollution
• more cars so otherwise there would be more carbon monoxide entering atmosphere
• improved engine technology
• catalytic converters have been introduced

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22
Q

Give one reason for having a max allowed prcentage of unburned hydrocarbons in exhaust fumes

A

Reduce health problems

Reduce global dimming

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23
Q

Give two effects of atmospheric pollution which are reduced by using catalystic converters

A
  • acid rain
  • respiratory problems
  • carbon monoxide
  • global dimming/smog
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24
Q

The catalyst in catalytic converters is a mixture in three elements. Where is the periodic table are these elements most likely to be found

A

Transition metals

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25
Q

Explainwhat happens to the yield of methanol if a temo higher than 250 is used

A

Smaller yield

Favours endothermic reaction

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26
Q

Sugggest why a catalyst is used in this industrial process

A

Less energy needed

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27
Q

Sugest the effect of using the catalyst on the equilibrium yield of methanol

A

No effect/change

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28
Q

Melamine is a ppolymer used to make non-disposable cups
Melamine does not melt when it is heated
Why

A 
Thermosetting polymer
Contains crosslinks (between polymer chains)
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29
Q

Suggest a suitable temp for the furnace in fractional distillation

A

Betwee 400-500

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30
Q

Suggest two reasons why bitumen is not used as fuel

A
  • too viscous
  • not very flammable
  • bp too high
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31
Q

Conditions needed to crack hydrocarbon molecules from the diesel oil fraction

A
  • high temp
  • steam
  • catalyst
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32
Q

Explain why large hydrocarbons cracked into smaller

A
  • greater demand
  • smaller
    • more uselful, better fuel, used to make alkenes, used to make polymers
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33
Q

How to show presence of lithium ions experiment

A

crush tablets or dissolve tablet (in water or acid) • clean wire
• place on wire
• place in (roaring / blue / non-luminous) flame
• observe flame colour
• crimsonflame

34
Q

What two pieces of meaasuring apparatus could the student use to fidn the rate of production of hydrogen gas

A
  • gas syringe

- stopclock/stopwatch

35
Q

Magnesium is fixed to some steel ships. Explain how this prevents the steel from rusting

A
  • mg more reactibe

- provides sacraficial protection

36
Q

Explain why aluminium windowframes do not corrode after they are made

A
  • al has coating of aluminium oxide

- protects metal from further corrosion

37
Q

Suggest reasons why wood is more sustainable than natural gas as a fuel for central heating boilers

A

wood is renewable
or
(natural) gas is finite
(burning) wood produces the same amount of carbon dioxide as the trees absorbed
or
(burning natural) gas increases the amount of carbon dioxide (in the atmosphere

38
Q

Name the function group of -COOH

A

Carboxylic acid

39
Q

Monomer -OH and -COOH join to produce a polyester and small molecule - what is it

A

Water

40
Q

Why does this type of polyester melt when it is heated

A
  • thermosoftening

- no cross-links

41
Q

Suggest why an outer skin is added to a polysester surf board

A 
Make it
	-harder
	-stronger
	tougher
-waterproof
42
Q

Describe a test to show that the drinking water contained aluminium ions

A

add sodium hydroxide (solution to water sample)
white precipitate (forms)
(precipitate which is) soluble in excess (NaOH)

43
Q

Plan an nvestigation to find the amss of dissolved solis in a fixed vollume of water

A

weigh (evaporating) basin / dish
• add measured volume of water
• weigh (evaporating) basin / dish and water
• heat to evaporate water
• reweigh
• repeat heating until constant mass obtained
• subtract mass of (evaporating) basin / dish from mass
• repeat and calculate a mean, discarding anomalous results • calculate the mass in 100 cm3 water if necessary

44
Q

Explain why organisms could not have evolved same way on titan as on earth- low o2 and co2 conc

A

Titan has) little / no oxygen
(so) photosynthesis has not occurred (on Titan)
(therefore) little / no carbon dioxide present (on Titan)
or
(therefore) oxygen-using animals cannot have evolved (on Titan)

45
Q

Explaine how methane a greenhouse gas, keeps titan warmer than otehr moons that do not have atmosphere

A

methane) allows short(er) wavelength radiation to pass through (from the sun)
(which is) re-emitted from the surface as long(er) wavelength radiation
(which is) absorbed (by methane in the atmosphere

46
Q

Why is a greater pressure not used in the haber process

A

• the energy costs would be
high(er)
• the equipment would need to be strong(er)
• high(er) pressures are (more) dangerous

47
Q

To test for sulfate ions the student added dilute hcl to copper sulfate solution. Name the solutio that would hsow the presence of sulfate ions when added to this micture

A

Barium chloride

48
Q

Why filter water

A

Remove undisolved solids

49
Q

How is liquid effluent processed

A

Aerobic biological treatment

50
Q

How is solid sewage sludge proposed

A

Anaerobic digestion

51
Q

Suggest reason why the total mass of processed solid sewage sludge increased between two dates

A

• the population increased
• more waste water produced • less untreated sewage
discharged

52
Q

Between 1992 and 2010 the proportion of processed solid sewage sludge used as fertiliser increased. Suggest why

A
  • increased demand for food (due to incrasing pop)
  • conserve energy/resources
  • landfill space is running out
  • increased demand for organic fertiliser
53
Q

Compare two molecules n term of
Structure and bonding
Their reactions

A
  • no. Atoms
  • no. Bonds
  • size of molecule
  • conbustion
  • reactions- addition
54
Q

Which was could one increase the distance between the spots

A
  • allow solvent front to travel further

- use a diff solvent

55
Q

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

A

-so that shade of green is the same

Or- green ink is a formulation

56
Q

What will def produce a smaller rf value if the solvent and paper are both changed

A
  • dye less soluble in new solvent

- more attracted new paper

57
Q

Describe how ceramic food plates are produced from clay

A
  • clay is shapes

- heated in furnace

58
Q

Ethanoic acid ionises in water

CH3COOH(aq) CH3COO-(aq) + H+(aq)

A
  • incomplete/partial ionisation

- reaction is reversible

59
Q

Methaoic acid

A

HCOOH

60
Q

CH3CH2COOH

A

Propanoic aci

61
Q

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

A

Ethyl ethanoate

62
Q

The student concluded that the large calcium carbonate lumps reacted more slowly than the small calcium carbonate lumps. How do the students result show that this conclusion is correct?

A

(for large lumps) a smaller number of moles of gas is collected in the same time or
(for large lumps) more time is needed to collect the same number of moles of gas
or
the line (of best fit for large lumps) is less steep

63
Q

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

A

Water

64
Q

Which gases from earths early atmosphere could have produced this element glycine for algea

A

Ammonia

Nitrogen

65
Q

Describe the shape and structure of dna

A

two polymer chains
four (different) monomers / nucleotides
(double) helix

66
Q

Give the name of the solvent used to dssolve the ions in this reaction

A

Water

67
Q

Explain why a change in pressure doesnt affect the colour of the equilibrium mixture

A

no change in equilibrium position

(because) no gases are present

68
Q

Suggest why uisng solar energy is a more suistainable way of generating electricity than burning oil

A

Solar is renewable source of energy

69
Q

solar energy may nit be able to replace the generation of electricity from fossil fuels completely? Suggestwhy

A
  • sunshine unreliable
  • increased demand for enrgy
  • lack of space
70
Q

Each student did the chomatography investigation differently. Rf values diff. How did the investigations differ

A

Dff solvent used

71
Q

What is the stationary phase in paper chromatography

A

Paper

72
Q

How can diff forms of poly(ethene) be produced from ethene

A

-use diff reaction conditions

73
Q

Explain why HDPE has a higher densiity than LDPE

A

HDPE polymer chains/ molecules are closer together

-more atoms per unit volume

74
Q

Name soluble salt produced when calcium phosphate reacts w/ nitric acid

A

Calcium nitrate

75
Q

Name soluble salt produced when calcium phosphate reacts w/ phosphoric acid

A

Triple superphosphate

76
Q

Suggest reasons why recylcling scrap copper is a more ssustainable way of obtaining copper than processing copper ores

A

recycling conserves copper ores
• recycling uses less energy
• recycling reduces waste
• mining / quarrying cause environmental impacts

77
Q

Describe how copper is extracted from low grade ores by phytoming

A

grow plants (on land containing copper ores)
plants are burnt (to produce ash)
ash dissolved in acid (to produce a solution of a copper compound)
electrolysis of solution (containing a copper compound) or
displacement (of copper) from solution (containing a copper compound)

78
Q

Ohytomining has not been widely used to extract copper - suggest why

A

high grade ores still available • land not available

• phytomining takes a long time • new technology

79
Q

Explain why the lines of best fit become horizontal

A
  • reactionhas stopped

- reactant is used up

80
Q

The activation energy for the reaction between zinc and sulfuric acid is lowered if a solution containinng meal ions is added. What is the most likely formula of. metal ions added

A

CU2+

81
Q

Describe conditions needed for cracking

A
  • high temp

- steam/catalyst

82
Q

Butanil can be produced from sugar solution by adding bacteria. Sugar solution is broken down in similar ways by bacteria and by yeast
Suggest reaction conditions needed

A
  • warm

- anaerobic conditions

chemistry (14 decks)

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