4.5 - Organic I

Question 1

pure substances - e.g. element or a compound, melt and boil at

Answer 1

fixed temperature

Question 2

mixtures melt and boil

Answer 2

over a range of temperatures.

Question 3

hydrocarbon

Answer 3

a compound of hydrogen and carbon only

Question 4

A functional group

Answer 4

an atom or a group of atoms that determine the chemical properties of a compound

Question 5

a homologous series is a group of substances with:

Answer 5

• the same general formula
• similar chemical properties because they have the same functional group
• a trend (graduation) in physical properties

Question 6

isomers

Answer 6

molecules with the same molecular formula but with a different structure

Question 7

crude oil

Answer 7

a mixture of hydrocarbons

Question 8

describe how the industrial process of fractional distillation separates crude oil into fractions

Answer 8

Crude oil is separated by fractional distillation.
Crude oil is heated and the oil evaporates.
The gas goes into the fractional distillation tower.
- As the gas rises the temperature falls.
Fractions with higher boiling points condense –> collected nearer the bottom of the tower

Question 9

1 carbon

Answer 9

meth-

Question 10

2 carbons

Answer 10

eth-

Question 11

3 carbons

Answer 11

prop-

Question 12

4 carbons

Answer 12

but-

Question 13

5 carbons

Answer 13

pent-

Question 14

6 carbons

Answer 14

hex-

Question 15

prefix for compounds

Answer 15

MEPB
monkeys eat peanut butter

Question 16

alkanes - ane

Answer 16

C-C
C-H

Question 17

alkenes - ene

Answer 17

C=C

Question 18

alcohols - ol

Answer 18

OH

Question 19

if given molecular formula is C2H6 what is the structural formula

Answer 19

C2 = two Cs
H6 - six Hs

CH3 CH3

Question 20

addition reactions involve

Answer 20

one product

Question 21

substitution reactions involve

Answer 21

two products

Question 22

combustion involves reaction of a

Answer 22

fuel with oxygen
if products are water and carbon dioxide its a hydrocarbon

Question 23

how does fractional distillation separate crude oil into fractions

Answer 23

• oil heated in fractionating column
• oil evaporates and condenses at diff temps
• hydrocarbons in crude oil are separated into fractions
• fractions contain molecules with similar number of carbon atoms
• vaporised oil rises up column and fractions are tapped off at different levels where they condense

Question 24

refinery gases used for

Answer 24

domestic heating and cooking

Question 25

gasoline used for

Answer 25

fuel for cars

Question 26

kerosene

Answer 26

fuel for aircraft

Question 27

diesel

Answer 27

fuel for trains and some cars

Question 28

fuel oil

Answer 28

fuel for large ships and in some power stations

Question 29

bitumen

Answer 29

surface roads and roofs

Question 30

order of main fractions

Answer 30

refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen

Question 31

short molecules /BP/viscosity of main fractions

Answer 31

short molecule - lower temp which it condenses - lower BP - less viscous

Question 32

colours darker at the bottom fractions

Answer 32

longer molecules

Question 33

fuel

Answer 33

substance that releases heat energy when burned

Question 34

products of complete combustion

Answer 34

CO2 and H2O produced

Question 35

products of incomplete combustion

Answer 35

carbon monoxide released - solid particles of soot(carbons) and unburnt fuel released

Question 36

incomplete combustion

Answer 36

not enough oxygen -> some fuel doesn't burn

Question 37

why is carbon monoxide poisonous

Answer 37

- prevents RBC carrying oxygen around body - lead to difficulty breathing and death

Question 38

in car engines how is oxides of nitrogen produced

Answer 38

temperature in high enough to allow nitrogen and oxygen from air to react - forms nitrogen monoxide or nitrogen dioxide

Question 39

how does combustion of impurities in hydrocarbon fuels results in sulphur dioxide

Answer 39

most fuels contain carbon and/or hydrogen and may contain sulphur - when fuels are burnt sulphur is oxidised to product sulphur dioxide

Question 40

how does sulphur dioxide and oxides of nitrogen contribute to acid rain

Answer 40

- when emitted they react with rain water to create H+ ions - acid corrodes rocks/buildings - alters soil pH in soil/rivers, affects ecosystem - corrodes limestones in statues

Question 41

how are long-chain alkanes converted to alkenes and shorter chain alkenes

Answer 41

hydrocarbons cracked to produce smaller and more useful molecules - heat hydrocarbons to vaporise them - passed over hot catalyst (silica) - mixed with steam and heated to high temp (600-700) so the thermal decomposition reactions occur

Question 42

alkenes general formula

Answer 42

CnH2n

Question 43

products of cracking

Answer 43

alkanes unsaturated hydrocarbons - alkenes

Question 44

alkanes general formula

Answer 44

CnH2n+2

Question 45

why are alkanes saturated hydrocarbons

Answer 45

contains no C=C bonds saturated - all carbons has max 4 bonds

Question 46

describe reaction of alkanes with halogens in pre scene of UV radiation

Answer 46

halogen + alkane --(UV)--> halogenoalkane + hydrogen halide

Question 47

functional group of alkenes

Answer 47

C=C

Question 48

why are alkenes classified as unsaturated hydrocarbons

Answer 48

contains one or more C=C double bonds

Question 49

describe reactions to produce dibromoalkanes

Answer 49

alkene + bromine --> dibromoalkanes - removal of C=C

Question 50

how can bromine water distinguish alkane and alkene

Answer 50

alkene - reacts with bromine water, orange --> colourless alkanes - doesn't reacts with bromine water, remains orange

Question 51

addition polymer is formed by

Answer 51

joining up many small molecules called monomers

Question 52

addition polymer drawing

Answer 52

- line through two brackets - removal of C=C - brackets with n - poly(__)

Question 53

problems in disposal of addition polymers

Answer 53

- unbiodegradable , microorganisms are unable to break them down since they are inert - produces toxic gases when burnt - CO2 releases when burnt, global warming

Question 54

Alkanes reaction with bromine

Answer 54

Substitution C3H7Br HBr

Question 55

Alkenes reaction with bromine

Answer 55

Addition C3H6Br2