PAPER 2 - PRACTICE QUESTIONS Flashcards
describe and explain the effect of an increase in temp on the rate of reaction
- 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
compare crcking and distillation
- cracking needs a catalyst and distillation doesnt
- distillation DOESNT involve a chemical change but cracking does
how is crude oil serperated by fractional distillation
- 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
what happens when an alkane burns
- combines with oxygen to make carbon dioxide and water
- exothermic so releases energy into environment
hows crude oil formed
biomass eg plankton burried in mud and compressed over a long period of time
describe and explain the trend in boiling points of the alkanes
- 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
why is cracking used in the fuel industry
- 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
evaluate the use of cruid oil and sugar to produce ethanol
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
describe how ethanol is produced from suagr solution
sugar is fermented in yeast in ANAEROBIC condition
describe how ethanol can be produced from alkenes
alkene mixed w steam at very high temps in presence of a catalyst
this high temp heats gas to generate a high pressure
describe how polymers such as poly(ethene) are produced
- 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
describe structure of dna
- 2 polymer chains twisted in a double helix that has 4 dif monomers known as nucleotides
describe how polymers such as poly(ester) are produced
- 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
explain how paper chromatography causes different pigments to serperate
- 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
plan a chromatography experiment to investigate the colour in an ink
- 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
describe natural processes that remove co2 from the earths atmosphere
- 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
describe how plamts and other organisms have chanage the atmosphere
- 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
describe and explain how the atmosphere today is dif from billions of years ago
- 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
explain and justify steps to treat water from resivoirs
- filtered first to remove solids sauch as small insoluable particles
- then have chemicals eg chlorine added to steralise and reduce number of mircrobes
explain how sea water is used to make potable water
- 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
describe how sewage water is treated
- screening - passes through metal grid to remove large bits
- sedimentation
heavier sink to bottom - sludge
liquid layer above - effluent - sludge is piped away and broken down by microbes anaerobically and effluenct broken down aerobically
- then sterilised to kill pathogens
how is copper made using phytomining
- 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
why are biological methods used to extract copper
- bc its running out
- doesnt use mining - bad for environment
explain how copper can be extracted from a sopper solution using scrap iron
- iron more reactive then copper
- iron displaces so copper ions reduced and copper forms
PAGE 24 PIAGRAM - SINCLAIR BOOKELT
explain the condition for the haber process
- 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
explain why thermosftening polymers melt when heated
- the polymer chain weak intermolecular forces that are easy to overcome when heated
explain why thermosetting polymers dont melt when heated
- the polymer chain has cross links which are very strong and require lots of energy to overcome
identify catalyst in haber process and why its used
- iron
- lowers activation energy
- cheap
- higher yield in shorted time
why is there less co2 and more ox in todays atmosphere
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
