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chemistry > PAPER 2 - PRACTICE QUESTIONS > Flashcards

PAPER 2 - PRACTICE QUESTIONS Flashcards

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1
Q

describe and explain the effect of an increase in temp on the rate of reaction

A
  • temp increase ror also increase
  • particles more kinetic so collide more freuwently
  • when they collide they will have enough activation energy for reaction to occur
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2
Q

compare crcking and distillation

A
  • cracking needs a catalyst and distillation doesnt
  • distillation DOESNT involve a chemical change but cracking does
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3
Q

how is crude oil serperated by fractional distillation

A
  • oild heated and hydrocarbons vaporise which enetrs colum at the bottom
  • hotter at bottom and cooler at top
  • vapour rises and cools
  • the hydrocarbons condense into a liquid at their specific boiling points
  • they all have dif boiling points so will condence and collect at dif levels
  • smallest hydrocarbons have lowest boiling points and collect as a gas at the top where temp is lower
  • larger have higher and collect at bottom where temp is higher
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4
Q

what happens when an alkane burns

A
  • combines with oxygen to make carbon dioxide and water
  • exothermic so releases energy into environment
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5
Q

hows crude oil formed

A

biomass eg plankton burried in mud and compressed over a long period of time

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6
Q

describe and explain the trend in boiling points of the alkanes

A
  • bigger the alkane the higher the bp
  • bc the molecules get bigger so the intermolecular forces increase
  • so it takes more energy for bonds to be overcome when alkane turns into gas
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7
Q

why is cracking used in the fuel industry

A
  • cracking is breaking larger molecules into smaller ones
  • large hydrocarbons arent useful and dont ignite easily or voletile so they dont flow
  • by braking them we get smaller ones which can be used as fuels
  • they are volatile and ignite easily which are idea properties for fuel
  • alkenes are also prodiced during cracking which can be useful to make polymers
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8
Q

evaluate the use of cruid oil and sugar to produce ethanol

A

suagr
- cheaper/ renewable/ carbon neutral/safe
- batch process slow/ lots of land to grwo crops/ labour / ethanol not pure
cruid oil
- non renewable/£££/releases carbon/ oil spillages
- faster and ethonal pure

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9
Q

describe how ethanol is produced from suagr solution

A

sugar is fermented in yeast in ANAEROBIC condition

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10
Q

describe how ethanol can be produced from alkenes

A

alkene mixed w steam at very high temps in presence of a catalyst
this high temp heats gas to generate a high pressure

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11
Q

describe how polymers such as poly(ethene) are produced

A
  • made from one tye of monomer called ethene
  • during addition polymerisation
  • the double bond between ethene monomers breaks and they bond together to form one long polymer chain
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12
Q

describe structure of dna

A
  • 2 polymer chains twisted in a double helix that has 4 dif monomers known as nucleotides
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13
Q

describe how polymers such as poly(ester) are produced

A
  • 2 dif monomers
  • one is alcohol -OH
  • the other is carboxilic acid -COOH
  • the functional groups react and form ester links and the polymer chain is formed
  • water is also given off
  • condensation polymerisation
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14
Q

explain how paper chromatography causes different pigments to serperate

A
  • solvent is the mobile phase which moves through the paper which is the stationary phase
  • dif pigments have dif solubilities and so different attractions to the paper
  • therefore dif pigments are carried dif distances so seperate
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15
Q

plan a chromatography experiment to investigate the colour in an ink

A
  • dots of known colours and dot of ink on the pencil origin line on chromatography paper
  • bottom of paper in water
  • the solvent would then rise up the paper
  • when near the top remove paper and leave to dry
  • compare positions of dots for known colours and ones form ink
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16
Q

describe natural processes that remove co2 from the earths atmosphere

A
  • plants take yup co2 and convert to glucose and starch in photosynthesis
  • co2 in atmosphere dissolve in sea water and produce hydrocarbonates
  • marine animals use carbonates to make shells and overtime the shells become sedimentary rocks
17
Q

describe how plamts and other organisms have chanage the atmosphere

A
  • plants take in co2 and release oxygen in photosynthesis
  • when plants die co2 trapped in rocks and fossil fuels
  • oxygen reacted with other molecules methane and ammonia
  • nitrogen produced between ammonia and nitrogen reactions
  • denitrifying bac prodiced nitrogen gas too
  • nitrogen builds up in atomsphere bc so unreactive
18
Q

describe and explain how the atmosphere today is dif from billions of years ago

A
  • less co2 bc absorbed by plants and fossil fuels and it dissolved into oceans to become rocks
  • today more oxyegn bc bc plants evolved and photosynthesis
  • today more nitrogen - produced by decay of organisms and break down of ammonia. its unreactive so lots in atmosphere
  • less water vapour bc when earth cooled it condenced and formed our oceans
19
Q

explain and justify steps to treat water from resivoirs

A
  • filtered first to remove solids sauch as small insoluable particles
  • then have chemicals eg chlorine added to steralise and reduce number of mircrobes
20
Q

explain how sea water is used to make potable water

A
  • when there is insufficient ground water - eg v hot countries
  • they have to desalinate the water
  • either by reverse osmosis or distillation
  • both v expensiuve and need lots of energy
21
Q

describe how sewage water is treated

A
  1. screening - passes through metal grid to remove large bits
  2. sedimentation
    heavier sink to bottom - sludge
    liquid layer above - effluent
  3. sludge is piped away and broken down by microbes anaerobically and effluenct broken down aerobically
  4. then sterilised to kill pathogens
22
Q

how is copper made using phytomining

A
  • plants grown on land w low grade copper ores
  • then harvested and burned to make ash
  • collected and added to an acid to dissolve and form copper solution
  • then electrolysis to extract the copper
23
Q

why are biological methods used to extract copper

A
  • bc its running out
  • doesnt use mining - bad for environment
24
Q

explain how copper can be extracted from a sopper solution using scrap iron

A
  • iron more reactive then copper
  • iron displaces so copper ions reduced and copper forms
25
Q

PAGE 24 PIAGRAM - SINCLAIR BOOKELT

A
26
Q

explain the condition for the haber process

A
  • temp of 450
    reversible and exothermic so higher temp would lower the yeild of ammonia as the endothermic reaction that breaks te ammonia down would increase
    but a lower temp would decrease the rate of reaction bc particles have less kinetic energy so collide slower
  • pressure of 200 atmospheres
    hgiher pressure would increase the yield of ammonia bc eq moved tp the right however high also is v ££ and dangerous
27
Q

explain why thermosftening polymers melt when heated

A
  • the polymer chain weak intermolecular forces that are easy to overcome when heated
28
Q

explain why thermosetting polymers dont melt when heated

A
  • the polymer chain has cross links which are very strong and require lots of energy to overcome
29
Q

identify catalyst in haber process and why its used

A
  • iron
  • lowers activation energy
  • cheap
  • higher yield in shorted time
30
Q

why is there less co2 and more ox in todays atmosphere

A

co2
* volcanic activity released water vapour
* the water vapour condensed to form oceans
* carbon dioxide dissolved in oceans
* carbonates produce sediments
* carbon locked up in sedimentary rocks
* carbon locked up in fossil fuels
water
* algae and plants evolved / appeared
* algae / plants absorbed carbon dioxide
* by photosynthesis
* which also released oxygen

chemistry (17 decks)

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