organic chemistry

Question 1

define a fuel

Answer 1

a substance that burns in air or oxygen to release a usable amount of energy

Question 2

define functional group

Answer 2

an atom of group of atoms in an organic molecule that largely determine the molecules properties and reactions

Question 3

define hydrocarbon

Answer 3

a compound that contains only carbon and hydrogen

Question 4

define homologous series

Answer 4

a series of compounds with similar chemical properties and the same general formula, in which each member contains on CH2 unit more than the previous number

Question 5

define structural isomer

Answer 5

a compound that has the same molecular formula, but a different structural formula

Question 6

incomplete combustion

Answer 6

occurs when supply of air/oxygen is insufficient, so CO2 not produced. water and carbon, or carbon monoxide and water are produced

Question 7

complete combustion

Answer 7

requires plentiful supply of air so that elements in fuel can fully react w excess oxygen. produce CO2 and water

Question 8

alkanes

Answer 8

a saturated hydrocarbon containing only single bonds between carbon atoms. general formula CnH2n+2

X decolourise bromine water
reacts in UV light
tetrahedral geometry - bond angle of 109.5 deg

Question 9

alkenes

Answer 9

an unsaturated hydrocarbon, containing one or more double bonds present between carbon atoms. general formula CnH2n

decolourises Br water from orange -> colourless
planar geometry - bond angle of 120 deg

Question 10

carboxylic acids

Answer 10

name ends in -oic acid
carbon in carboxyl functional group -COOH, is carbon no 1 in parent chain

Question 11

alcohols

Answer 11

name ends in -anol
contains one hydroxyl -OH grp on chain

Question 12

primary, sec, tert alcohols

Answer 12

primary = carbon w -OH is bonded to no or 1 carbon atom and oxidise to carboxylic acids
secondary = carbon bonded to 2 and oxidise to form ketones
tertiary = carbon bonded to 3 other

Question 13

alkynes

Answer 13

unsaturated hydrocarbon, containing one or more triple bond present between carbon atoms. general formula CnH2n-2

decolourises bromine water
linear geom - bond angles 180 deg

Question 14

amines

Answer 14

replace last -e of alkane w -amine
primary amines have structure alkyl group-NH2 (func grp)
amino- prefix w higher func grp

Question 15

amides

Answer 15

contain -CONH2 grp always on carbon 1 of parent chain
suffix -amide and prefix amido-

Question 16

aldehydes

Answer 16

have the C=O bond at start of parent chain
contains -CHO functional group
name = add -al onto corresponding alkane

H-C=O

Question 17

ketones

Answer 17

contain a carbonyl group, C=O
can be anywhere in chain
alkane ending with -one eg. alkanone

Question 18

priority in naming

Answer 18

carboxylic acid
ester
amide
aldehyde
ketone
alcohol
amine
alkene
alkyne
alkane
haloalkane
branches

Question 19

esters

Answer 19

contain ester func group =OCO-
formed from reaction of carboxylic acid and an alcohol
alkyl group (off the single oxygen) - yl hydrocarbon chain attaching to -COO, oate

Question 20

uses of ethanol

Answer 20

solvent in perfumes, inks and glues
fuel to make biofuel
to make ester, used in food flav.
alcoholic drinks

Question 21

prod of ethanol from fermentation of glucose

Answer 21

biological method
glucose -(yeast catalyst)-> ethanol + carbon dioxide

cheaper, sugar from sugar cane=renewable BUT slow, batch process and impure ethanol produced

Question 22

prod of ethanol from hydration

Answer 22

chemical method
ethene + steam -> ethanol

fast, continuous, pure ethanol produced BUT expensive, uses ethene from crude oil = non renewable

Question 23

addition polymerisation

Answer 23

alkene molecules = monomers
under pressure and with a catalyst, double bond b/w monomers breaks and bonds form to form poly____

Question 24

define monomer

Answer 24

molecule that can be bonded to other identical molecules to form a polymer

Question 25

substitution reaction

Answer 25

alkanes = saturated so undergo limited chemical reactions alkane + halogen -(UV light)->> haloalkane + hydrogen halide

Question 26

producing alcohol from haloalkane

Answer 26

haloalkane + OH- -> alcohol + halide ion via sodium or potassium hydroxide solution

Question 27

addition reactions of alkenes

Answer 27

alkene + hydrogen halide -> haloalkane alkene + hydrogen -> alkane (need nickel catalyst and 150 deg for HYDROGENATION) alkene + water -> alkanol (need phosphoric acid catalyst, 300 deg, 60-70 atm for HYDRATION)

Question 28

formation of esters

Answer 28

reversible reaction reaction b/w alkanol and acid condensation reaction = produce h2o esterification reaction need H2SO4 catalyst

Question 29

oxidation of prim and sec alcohols

Answer 29

primary: oxid by acidified permanganate (H+/MnO4-) or dichromate solution (H+/Cr2O72-) to produce aldehydes and carboxylic acids eg. ethanol -> ethanal -> ethanoic acid sec: oxid by same oxidising agents to form ketone (C=O)

Question 30

bonding b/w alkanes based w dispersion forces

Answer 30

-molecules can be closer to one another, can pack more closely depending on shape -larger molecules have more regions of charge to attract each other -disp forces strength = increased

Question 31

solubility of organic molecules in water

Answer 31

small alcohols, amines, aldehydes, ketones, carboxylic acids, amides = able to form H bonds w water so soluble water dissolves organic molecules by forming dipole-dipole attraction and H bonds w them

Question 32

elastomers

Answer 32

type of polymer can be stretched or deformed can regain their shape only a few cross links = sulfur bridges

Question 33

thermosetting

Answer 33

type of polymer cross links b/w chains much higher melting points cannot be remoulded rigid and inflexible eg. used on kitchen bench covering

Question 34

thermoplastic aka thermosoftening

Answer 34

type of low density polymer chains loosely tangles together no cross links low melting point can be remoulded eg. plastic bags, cling wrap

Question 35

LDPE

Answer 35

low density polyethene formed under high temps and pressure branched chains = X fit together well so amorphous low MP soft and flexible

Question 36

HDPE

Answer 36

high density poly ethene formed using catalyst at low temp + pressure unbranched chains fit together much better, more crystalline, less amorphous form harder substance eg. wheelie bins, classroom chairs