Organic chemistry

Question 1

structures of methane, ethane, ethene, ethanol, ethanoic acid

Answer 1

o 1​ carbon​ ​has​ ​the​ ​prefix​ ​of:​ ​Meth-
o 2​ ​carbons:​ ​Eth-
o 3​ ​carbons:​ ​Prop-
o 4​ ​carbons:​ ​But-
o Remember​ ​the​ ​first​ ​4​ ​prefixes​ ​using​ ​MEPB​ ​Monkeys​ ​Eat​ ​Peanut​ ​Butter
-suffix​ ​of​ ​any​ ​compound​ ​refers​ ​to​ ​the​ ​functional​ ​group
o Alkanes​ ​–ane​ ​(C-C)​ ​e.g.​ ​ethane
o Alkenes​ ​–ene​ ​(C=C)​ ​e.g.​ ​ethene
o Alcohols​ ​–ol​ ​(OH)​ ​e.g.​ ​ethanol
o Carboxylic​ ​acids​ ​–anoic​ ​acid​ ​(-COOH)​ ​e.g.​ ​ethanoic​ ​acid

Question 2

type of compound present, given a chemical name ending in -ane, -ene, -ol, or -oic acid or a molecular structure

Answer 2

● -Ane​ ​:​ ​alkane
o Functional​ ​group​ ​(same​ ​group​ ​of​ ​atoms​ ​in​ ​each​ ​molecule​ ​that​ ​makes​ ​an alkane)​ ​is​ ​C-H​ ​/​ ​C-C​ ​(NOT​ ​C=C) 
● -Ene​ ​:​ ​alkene
o Functional​ ​group​ ​is​ ​C=C 
● -Ol​ ​:​ ​alcohol
o Functional​ ​group​ ​is​ ​OH 
● -Oic​ ​acid​ ​:​ ​carboxylic​ ​acid
o Functional​ ​group​ ​is​ ​COOH

Question 3

Name and draw the structural formulae of the esters which can be made from unbranched alcohols and carboxylic acids, each containing up to four carbon atoms

Answer 3

o Alcohol​ ​+​ ​carboxylic​ ​acid​ ​->​ ​ester​ ​+​ ​water
o ​Methanol​ ​+​ ​Ethanoic​ ​acid​ ​->​ ​Methyl​ ​Ethanoate​ ​+​ ​H2O
● How​ ​to​ ​name​ ​esters
o (prefix​ ​of​ ​alcohol​ ​+​ ​yl)​ ​+​ ​(name​ ​of​ ​carboxylic​ ​acid​ ​minus​ ​the​ ​“oic​ ​acid”​ ​+ oate)
o E.g.​ ​Meth-yl​ ​Ethan-oate
● the​ ​alcohol​ ​part​ ​is​ ​to​ ​the​ ​right​ ​normally​ ​with​ ​an​ ​H​ ​from
the​ ​–OH​ ​functional​ ​group​ ​being​ ​lost.
● The​ ​carboxylic​ ​acid​ ​part​ ​is​ ​to​ ​the​ ​left​ ​with​ ​an​ ​OH​ ​from
the​ ​–COOH​ ​functional​ ​group​ ​being​ ​lost
● H​ ​+​ ​OH​ ​→​ ​H​2O​ ​ ​(a​ ​by-product.

Question 4

fuels

Answer 4

coal, natural gas and petroleum

Question 5

methane as the main constituent of natural gas

Answer 5

• methane as the main constituent of natural gas

- methane=​ ​CH4​

Question 6

petroleum

Answer 6

Petroleum is a mixture of hydrocarbons

Question 7

properties of molecules within a fraction

Answer 7

●The​ ​shorter​ ​the​ ​molecules,​ ​the​ ​lower​ ​the​ ​temperature​ ​at​ ​which​ ​that​ ​fraction evaporates​ ​or​ ​condenses​ ​–​ ​and​ ​the​ ​lower​ ​its​ ​boiling​ ​point.
● Shorter​ ​the​ ​molecules,​ ​the​ ​less​ ​viscous​ ​it​ ​is.​ ​(more​ ​runny)

Question 8

uses of the fractions

Answer 8

– refinery gas for bottled gas for heating and
cooking
– gasoline fraction for fuel (petrol) in cars
– naphtha fraction for making chemicals
– kerosene/paraffin fraction for jet fuel
– diesel oil/gas oil for fuel in diesel engines
– fuel oil fraction for fuel for ships and home heating systems
– lubricating fraction for lubricants, waxes and polishes
– bitumen for making roads

Question 9

Homologous series

Answer 9

a ‘family’ of similar compounds with similar chemical properties due to the presence of the same functional group

Question 10

general characteristics of a homologous series

Answer 10

• Same general formula
• Similar chemical properties
• Common methods of preparation

Question 11

Describe and identify structural isomerism

Answer 11

• Isomers are compounds that have same molecular formula but different structural formula.
• Properties quite simmilar
• M.p and B.p differ

Question 12

properties of Alkanes (exemplified by methane)

Answer 12

● Generally​ ​unreactive,​ ​except​ ​in​ ​terms​ ​of​ ​burning

Question 13

bonding in alkanes

Answer 13

• Contain single bond

- General formula: Cn H2n +2

Question 14

substitution reactions of alkanes with chlorine

Answer 14

● Halogen​ ​+​ ​alkane​ ​–(UV)->​ ​halogenoalkane​ ​+​ ​hydrogen​ ​halide oe.g.​​Br2​​​​+​​C2​H​​6​​​​​-(UV)->​​C2​H​​5B​r​​+​​HBr
● Must​ ​be​ ​in​ ​the​ ​presence​ ​of​ ​ultraviolet​ ​radiation​ ​(UV)

Question 15

manufacture of alkenes and of hydrogen by cracking

Answer 15

● Hydrocarbons​ ​can​ ​be​ ​cracked​ ​to​ ​produce​ ​smaller,​ ​more​ ​useful​ ​molecules.​ ​This process​ ​involved​ ​heating​ ​the​ ​hydrocarbons​ ​to​ ​vaporise​ ​them.
● The​ ​vapours​ ​are:
o Either​ ​passed​ ​over​ ​a​ ​hot​ ​catalyst​ ​(silica​ ​or​ ​alumina)
o Mixed​ ​with​ ​steam​ ​and​ ​heated​ ​to​ ​a​ ​very​ ​high​ ​temperature​ ​(temperature
in​ ​the​ ​range​ ​of​ ​600-700 ̊C)​ ​so​ ​that​ ​thermal​ ​decomposition​ ​reactions​ ​can occur.
● The​ ​products​ ​of​ ​cracking​ ​include​ ​shorter​ ​chain​ ​alkanes​ ​and​ ​alkenes​ ​(or​ ​hydrogen)

Question 16

properties of alkenes

Answer 16

● Generally:
○ Addition​ ​reactions
○ Involves​ ​the​ ​removal​ ​of​ ​C=C​ ​double​ ​bond
○ C=C​ ​is​ ​very​ ​reactive​ ​and​ ​can​ ​easily​ ​react​ ​to​ ​form​ ​–C-C-
● reaction​ ​​ ​with​ ​bromine:
○ alkene​ ​+​ ​bromine​ ​→​ ​dibromoalkane
○ E.g.​ ​Ethene​ ​+​ ​bromine​ ​→​ ​1,2-dibromoethane
● reaction​ ​with​ ​steam:
○ alkene​ ​+​ ​steam​ ​→​ ​alcohol
○ E.g.​ ​Ethene​ ​+​ ​steam​ ​→​ ​ethanol
● reaction​ ​with​ ​hydrogen:
○ alkene​ ​+​ ​hydrogen​ ​→​ ​alkane
○ E.g.​ ​Ethene​ ​+​ ​hydrogen​ ​→​ ​ethane

Question 17

Distinguish between saturated and unsaturated hydrocarbons:

Answer 17

o Unsaturated​ ​=​ ​contain​ ​one​ ​or​ ​more​ ​C=C​ ​double​ ​bonds​ ​e.g.​ ​alkenes
o Saturated​ ​=​ ​contain​ ​no​ ​C=C​ ​double​ ​bonds​ ​e.g.​ ​alkanes

reaction​ ​with​ ​aqueous​ ​bromine:
o Unsaturated​ ​hydrocarbons​ ​react​ ​with​ ​bromine​ ​in​ ​an​ ​addition​ ​reaction, decolourising​ ​it​ ​(​orange​​ ​to​ ​colourless)​ ​–​ ​shown​ ​above​ ​with​ ​the​ ​example of​ ​ethene​ ​reacting​ ​with​ ​bromine
o Saturated​ ​hydrocarbons​ ​do​ ​not​ ​react​ ​with​ ​bromine​ ​and​ ​therefore​ ​the
solution​ ​will​​ ​remain​ ​orange

Question 18

formation of poly(ethene) as an example of addition polymerisation of monomer units

Answer 18

● Alkenes​ ​can​ ​be​ ​used​ ​to​ ​make​ ​polymers​ ​such​ ​as​ ​poly(ethene)​ ​by​ ​addition polymerisation.​ ​In​ ​this​ ​reaction,​ ​many​ ​small​ ​molecules​ ​(monomers)​ ​join​ ​together to​ ​create​ ​very​ ​large​ ​molecules​ ​(polymers).

Question 19

manufacture of ethanol by fermentation and by the catalytic addition of steam to ethene

Answer 19

● Fermentation:
o The​ ​fermentation​ ​of​ ​glucose
o conditions:​ ​​ ​temperature​ ​of​ ​about​ ​30 ̊C,​ ​anaerobic​ ​conditions​ ​(no​ ​oxygen)
and​ ​using​ ​the​ ​enzymes​ ​in​ ​yeast
o equation:​​ ​glucose​ ​→​ ​ethanol​ ​+​ ​carbon​ ​dioxide
● Steam:
o Reacting​ ​ethene​ ​with​ ​steam
o conditions:​ ​phosphoric​ ​acid​ ​catalyst,​ ​temperature​ ​of​ ​about​ ​300 ̊C​ ​and​ ​a
pressure​ ​of​ ​about​ ​60-70​ ​atm
o equation:​ ​​ethene​ ​+​ ​steam​ ​→​ ​ethanol

Question 20

advantages and disadvantages of these two methods of manufacturing ethanol

Answer 20

● Fermentation
o Advantages
▪Renewable​ ​raw​ ​materials, Warm,​ ​normal​ ​pressure​ ​(inexpensive), Little​ ​energy​ ​needed
o Disadvantages
▪ Batch​ ​process​ ​(stop-start), A​ ​lot​ ​of​ ​workers​ ​needed, Slow, Impure​ ​–​ ​needs​ ​treatment
● Steam
o Advantages
▪ Continuous​ ​process​ ​(runs​ ​all​ ​the​ ​time), Few​ ​workers​ ​needed, Fast, Pure
o Disadvantages
▪ Non-renewable​ ​raw​ ​materials, High​ ​temperature​ ​and​ ​pressure​ ​(expensive), A​ ​lot​ ​of​ ​energy​ ​needed

Question 21

properties of ethanol in terms of burning

Answer 21

● Burning​ ​in​ ​air​ ​or​ ​oxygen​ ​(complete​ ​combustion) oCH3​C​H2​O​H​​+​​3O​2​​​->​​2CO​2​​​+​​3H2​O​
o Can​ ​be​ ​used​ ​as​ ​a​ ​fuel​ ​in​ ​this​ ​way​ ​(this​ ​reaction​ ​produces​ ​heat​ ​energy) o Burns​ ​in​ ​a​ ​good​ ​supply​ ​of​ ​oxygen

Question 22

Uses of ethanol

Answer 22

as a solvent and as a fuel

Question 23

properties of aqueous ethanoic acid

Answer 23

● Ethanoic​ ​acid​ ​is​ ​a​ ​member​ ​of​ ​the​ ​carboxylic​ ​acids,​ ​they​ ​have the​ ​functional​ ​group​ ​–COOH.
● First​ ​four​ ​members​ ​are:​ ​methanoic​ ​acid,​ ​ethanoic​ ​acid, propanoic​ ​acid​ ​and​ ​butanoic​ ​acid
-Dissolves in water to produce an acidic solution

Question 24

Formation of ethanoic acid by the oxidation of ethanol by fermentation and with acidified Potassium manganate(VII)

Answer 24

● Ethanol​ ​reacts​ ​with​ ​oxygen​ ​in​ ​the​ ​air​ ​to​ ​form​ ​ethanoic​ ​acid​ ​(microbial​ ​oxidation)
● Ethanol​ ​reacts​ ​with​ ​acidified​ ​potassium​ ​manganate(VII)​ ​to​ ​form​ ​ethanoic​ ​acid
(under​ ​reflux)

Question 25

ethanoic acid as a typical weak acid

Answer 25

● A​ ​typical​ ​weak​ ​acid ● this​ ​means​ ​ethanol​ ​will​ ​release​ ​some​ ​H​+​​ ​ions​ ​in​ ​solution,​ ​but​ ​will​ ​not​ ​fully dissociate​ ​(loses​ ​the​ ​H​+​​ ​from​ ​the​ ​COOH​ ​group)

Question 26

reaction of a carboxylic acid with an alcohol in the | presence of a catalyst to give an ester

Answer 26

-Carboxylic​ ​acids​ ​react​ ​with​ ​alcohols​ ​in​ ​the​ ​presence​ ​of​ ​an​ ​acid​ ​catalyst​ ​to produce​ ​esters - ​have​ ​the​ ​functional​ ​group​ ​–COO-. -Name: o first​ ​part​ ​is​ ​from​ ​alcohol​ ​e.g.​ ​methanol​ ​→​ ​methyl o second​ ​part​ ​is​ ​from​ ​carboxylic​ ​acid​ ​e.g.​ ​butanoic​ ​acid→​ ​butanoate

Question 27

Polymers

Answer 27

large molecules built up from small units (monomers)

Question 28

typical uses of • plastics and of man-made fibres such as nylon and Terylene

Answer 28

-Plastics: o Plastic​ ​bags o Clingfilm o Buckets,​ ​other​ ​plastic​ ​tools -Man-made​ ​fibres​ ​such​ ​as​ ​nylon​ ​and​ ​Terylene: o Drawn​ ​into​ ​very​ ​fine​ ​fibres​ ​and​ ​woven​ ​into​ ​cloth​ ​for​ ​clothing o Other​ ​natural​ ​fibres​ ​(e.g.​ ​cotton)​ ​can​ ​be​ ​mixed​ ​with​ ​nylon​ ​or​ ​polyester fibres​ ​to​ ​make​ ​a​ ​soft​ ​but​ ​hard-wearing​ ​cloth

Question 29

differences between condensation and addition polymerisation

Answer 29

- Addition​ ​polymerisation​ ​involves​ ​the​ ​removal​ ​of​ ​a​ ​C=C​ ​double​ ​bond​ ​to​ ​form​ ​a –C-C-​ ​bond,​ ​i.e.​ ​it​ ​joins​ ​up​ ​unsaturated​ ​molecules​ ​to​ ​form​ ​a​ ​long​ ​saturated molecule - Condensation​ ​polymerisation​ ​involves​ ​the​ ​reaction​ ​of​ ​two​ ​different​ ​functional groups​ ​to​ ​form​ ​one​ ​long​ ​molecule​ ​by​ ​the​ ​removal​ ​of​ ​a​ ​small​ ​molecule,​ ​such​ ​as water​ ​H​2O​ - This​ ​means​ ​that​ ​there​ ​can​ ​be​ ​more​ ​than​ ​one​ ​monomer​ ​used​ ​in condensation​ ​polymerisation​ ​(unlike​ ​addition​ ​which​ ​only​ ​uses​ ​one)

Question 30

formation of nylon (a polyamide) and Terylene (a polyester) by condensation polymerisation

Answer 30

...

Question 31

pollution problems caused by non-biodegradable plastics

Answer 31

● Unable​ ​to​ ​biodegrade,​ ​because​ ​the​ ​polymers​ ​that​ ​form​ ​these​ ​plastics​ ​are​ ​inert​ ​/ unable​ ​to​ ​react​ ​therefore,​ ​microorganisms​ ​and​ ​bacteria​ ​are​ ​unable​ ​to​ ​break them​ ​down o Thus,​ ​the​ ​landfills​ ​are​ ​bad​ ​for​ ​the​ ​environment​ ​as​ ​the​ ​plastics​ ​will​ ​remain in​ ​the​ ​ground,​ ​unable​ ​to​ ​break​ ​down/decompose ● They​ ​produce​ ​toxic​ ​gases​ ​when​ ​they​ ​are​ ​burned o Carbon​ ​dioxide​ ​is​ ​also​ ​released​ ​–​ ​which​ ​adds​ ​to​ ​global​ ​warming

Question 32

Proteins and carbohydrates

Answer 32

constituents of food

Question 33

proteins

Answer 33

possessing the same (amide) linkages as nylon but with different units

Question 34

Structure of protein

Answer 34

...

Question 35

hydrolysis of proteins to amino acids.

Answer 35

● Hydrolysis​ ​is​ ​the​ ​splitting​ ​up​ ​of​ ​a​ ​molecule​ ​using​ ​water ● Hydrolysis​ ​of​ ​polymers​ ​results​ ​in​ ​the​ ​formation​ ​of​ ​their​ ​monomers ● In​ ​the​ ​case​ ​of​ ​proteins,​ ​when​ ​you​ ​add​ ​water​ ​to​ ​split​ ​up​ ​this​ ​natural​ ​polymer,​ ​you will​ ​get​ ​amino​ ​acids​ ​(the​ ​monomers​ ​that​ ​form​ ​the​ ​proteins)

Question 36

complex carbohydrates

Answer 36

● A​ ​large​ ​number​ ​of​ ​sugar​ ​units​ ​(diols)​ ​joined​ ​together​ ​by​ ​condensation polymerisation,​ ​e.g.​ ​a​ ​polyester​ ​with​ ​–O-​ ​linkages

Question 37

hydrolysis of complex carbohydrates

Answer 37

● Acids​ ​or​ ​enzymes​ ​to​ ​give​ ​simple​ ​sugars ● similarly​ ​to​ ​proteins,​ ​complex​ ​carbohydrates​ ​can​ ​be​ ​broken​ ​down​ ​into​ ​their monomers​ ​(simple​ ​sugars)​ ​using​ ​water​ ​with​ ​acids/enzymes

Question 38

fermentation of simple sugars to produce ethanol (and carbon dioxide).

Answer 38

● Produce​ ​ethanol​ ​(and​ ​carbon​ ​dioxide) ● sugar​ ​(glucose)​ ​→​ ​ethanol​ ​+​ ​carbon​ ​dioxide ● conditions:​ ​yeast​ ​enzyme,​ ​around​ ​30°C,​ ​anaerobic​ ​conditions​ ​(no​ ​oxygen)

Question 39

usefulness of chromatography in separating and identifying the products of hydrolysis of carbohydrates and proteins

Answer 39

● Chromatography​ ​is​ ​used​ ​to​ ​separate​ ​a​ ​mixture​ ​of​ ​molecules,​ ​therefore​ ​when​ ​you hydrolyse​ ​large​ ​molecules​ ​(polymers)​ ​like​ ​carbohydrates​ ​and​ ​proteins,​ ​you​ ​are left​ ​with​ ​a​ ​mixture​ ​of​ ​their​ ​monomers o Thus,​ ​chromatography​ ​can​ ​be​ ​used​ ​to​ ​separate​ ​and​ ​identify​ ​these monomers​ ​by​ ​their​ ​Rf​ ​values o sugars​ ​and​ ​amino​ ​acids​ ​will​ ​not​ ​produce​ ​visible​ ​spots,​ ​so​ ​once​ ​the chromatogram​ ​is​ ​dry,​ ​you​ ​need​ ​to​ ​spray​ ​it​ ​with​ ​a​ ​locating​ ​agent (Ninhydrin​ ​produces​ ​purple​ ​spots​ ​with​ ​amino​ ​acids​ ​and​ ​resorcinol​ ​makes coloured​ ​spots​ ​with​ ​sugars)