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OCR GCSE C4-C6 > C6.2 (2) > Flashcards

C6.2 (2) Flashcards

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1
Q

define a polymer

A

large molecules built up from small units (or monomers)

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2
Q

how does addition polymerisation work?

in terms of bonds

A
  • C=C double bond in alkenes is removed to produce a C-C single bond
  • the bonds then join with unsaturated molecules to form a long saturated polymer
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3
Q

how do you produce an addition polymerisation reaction?

A

react alkenes together at high pressure and a catalyst

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4
Q

what is special about addition polymerisation reactions compared to condensation polymerisation?

A
  • addition polymerisation only produces one product
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5
Q

how would you generally represent the product of an addition polymerisation reaction?

A

as a repeating unit (so the alkane , with two lines sticking out of the bracket), and a small n

  • REMEMBER ALKANE NLY HAS ONE LINE BETWEEN THEM AS BONDS HAVE OPENED UP *
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6
Q

what does the polymer name depend on?

eg. if propene is monomer, what is the polymer name?

A

depends on the name of the monomer

  • propene becomes poly(propene)
  • MONOMER NAME REMAINS SAME, BUT BOND DIAGRAM DOES NOT*
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7
Q

what is an addition polymerisation reaction?

A

when (only 1 type of) small monomers (alkenes) join together to form one large polymer (saturated hydrocarbon chain)

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8
Q

what is a condensation reaction?

A

two molecules reacting together to produce one large molecule and a water molecule

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9
Q

how many functional groups must there be within a monomer for it to react? (during a condensation reaction)

A
  • at least 2
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10
Q

how many monomers does each polymer (produced by a condensation reaction) usually contain?

A

100s or 1000s of monomers

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11
Q

what functional groups react together to produce a polyester?
(and how many of each one)

A

2 -OH groups (from alcohols) - HYDROXYL group

2 -COOH groups (from carboxylic acids) - CARBOXYL group

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12
Q

what are the produced when a polyester is formed?

A
  • an ester group ‘‘-COO-“
  • water
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13
Q

what functional groups react together to produce a polyamide? - and how many of each one ,k
(and what makes up an amide group)

A

2 carboxyl groups (-COOH)

2 animo groups (-NH2)

-CONH

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14
Q

what is a real life example of a polyamide?

A

a protein

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15
Q

explain how water is produced when a polyester is made

A
  • OH lost off COOH group
  • H lost of OH group
  • CO and O join together to make a polyester
  • OH and H lost join to form water
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16
Q

how do you represent a polymer after a condensation reaction?

A

draw repeating units with block diagrams (each block would represent a hydrocarbon group)
mainly draw repeating unit + n at the bottom

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17
Q

what 3 factors are needed to carry out a condensation reaction?

A
  • high pressure
  • high temperature
  • with a catalyst
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18
Q

how would you produce a polyester in a school lab?

A
  • heat together an alcohol + carboxylic acid

in presence of an acid catalyst

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19
Q

uses of polyesters?

A

clothing/fizzy drink bottles

ie. a polyester named PET

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20
Q

uses of polyamides?

A

clothing/ carpets

ie. polyamide named nylon

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21
Q

what is DNA?

A

a polymer made from four different monomers (called nucleotides)

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22
Q

what does a nucleotide (in DNA) consist of?

A
  • a phosphate group (circle)
  • deoxyribose sugar (pentagon)
  • an organic base (rectangle)
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23
Q

what bond forms between opposite bases within DNA?

A

hydrogen bonds

24
Q

how many naturally occuring proteins are there?

A

20

25
Q

what does sucrose consist of?

A

simple sugars joined together (glucose + fructose)

26
Q

what determines the reactions of organic compounds?

A

the generality of reactions of functional groups

BASICALLY FUNCTIONAL GROUPS CONTROL HOW ORGANIC COMPOUNDS REACT

27
Q

define crude oil

A

a complex mixture of hydrocarbons (mainly alkanes)

28
Q

why is crude oil able to be separated using fractional distillation?

A

as the different hydrocarbons that make up the mixture have different boiling points

29
Q

how is crude oil made?

A
  • from dead marine creatures
  • pressure and temperature turned them into crude oil
30
Q

explain (in terms of intermolecular forces), why fractional distillation is used to separate crude oil

A
  • alkanes have different boiling points SINCE
  • they have different numbers of carbon molecules (and therefore have different sized carbon chains)
  • longer chained alkanes have a higher boiling point
  • as the intermolecular forces between them are stronger
31
Q

why do alkanes within crude oil have different boiling points?

A
  • have different number of carbon molecules
  • which affects chain length
  • a longer chain length means intermolecular forces between them are stronger
  • More energy is required to break these bonds
  • and so has a high boiling point
32
Q

what is the mnemonic to remember the name of the fractions?

A

licking
petrol
probably
does
harm
for
billy

33
Q

describe the separation of crude oil by fractional distillation

A
  • oil is heated in the fractioning column
  • it evaporates
  • hydrocarbons condense on designated fraction + are extracted
  • each fraction contains substances with similar boiling points
34
Q

which hydrocarbons have the lowest boiling points?

A
  • refinery gases
    ie. methane, ethane, propane, butane

(leaves through LPG at the top)

35
Q

fractions are largely a ……… of compounds of formula …………. which are a member of the ……… homologous series

A

mixture, CnH2n+2, alkane

36
Q

crude oil is the ……… source of …………… and is a …………… for the ……………….. industry

A

main, hydrocarbons, feedstock, petrochemical

37
Q

how is modern life crucially dependant upon hydrocarbons?

A

each fraction obtained is used for something

ie. for plastics/oil/petrol

38
Q

what is bitumen used for?

A

making roads

39
Q

what is the paraffin fraction used for?

A

jet fuel

40
Q

what kind of resource is crude oil?

A

finite resource

41
Q

what is cracking?

A

a chemical reaction where large alkane molecules are converted to smaller alkene and alkane molevules

42
Q

what are the conditions required for cracking to occur?

A

high temperature, catalyst, closed system

43
Q

describe what happens in cracking?

A
  • hydrocarbons (separated by fractional distillation) are
    heated to a high temperature
  • then passed over a catalyst of alumina or silica
44
Q

what bonds break during cracking?

A

the covalent bonds between the atoms (in large alkane molecules) break

45
Q

why is cracking carried out?

A
  • fractional distillation produces more long chained alkanes than short chained
  • which are less useful
  • cracking helps to produce more short chained (which are more useful)
46
Q

what are small alkanes generally used for?

A

fuels

47
Q

what are alkenes generally used for?

A

making plastic polymers

48
Q

how does a chemical cell work?

A

produces a potential difference until the reactants are used up

49
Q

give the advantages of hydrogen-oxygen fuel cells

A
  • no combustion -> no greenhouse effects (only waste product is water)
  • greater efficiency + is simple
  • hydrogen and oxygen are abundant in the air
50
Q

disadvantages of hydrogen-oxygen fuel cells

A
  • need fossil fuels to produce hydrogen (not found by itself on earth)
  • storage of hydrogen fuel is difficult
  • hydrogen fuel is highly explosive
51
Q

what is the word equation to model the chemical reaction occurring in a hydrogen-oxygen cell

A

hydrogen + oxygen -> water

52
Q

how do hydrogen-oxygen fuel cells work?

A
  • hydrogen enters cell
  • it becomes oxidised at the anode (-)
  • electrons lost then travel around the external circuit to the cathode (generating
    electricity)
  • to the cathode (as there is a potential difference)
  • hydrogen ions travel through the proton exchange membrane (a special membrane which allows only H+ through, not H^2 or O^2
  • they then react with the oxygen coming from other inlet
  • and produce water
53
Q

what charges do each electrodes have in an hydrogen-oxygen fuel cell?

A

anode (-)
cathode (+)
- opposite to electrolysis
- electrons are always transferred from anode to cathode (in both electrolysis and fuel cells)

54
Q

what are the order of fractions (shorter hydrocarbon chains -> longer).

A

LPG
Petrol
Paraffin
Diesel
Heating Oil
Fuel Oil
Bitumen

Licking petrol probably does harm for Billy

55
Q

octane is separated lower down the fraction in column than methane. explain why, using ideas about intermolecular forces. (3)

A

any 3 from:
- octane is a longer-chained hydrocarbon
- longer-chained hydrocarbons have stronger IM forces than shorter-changed ones
- stronger IM forces means more energy required to break bonds
- octane has a higher boiling point (requires more energy)
- fractioning column is hotter at the bottom

not in markscheme but i think it’s important to understand:
- octane condenses lower down the column as it has a higher boiling point, so it cannot still be a gas at lower temps like methane

OCR GCSE C4-C6 (12 decks)

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