organic chemistry

Question 1

define hydrocarbon

Answer 1

compound of hydrogen and carbon only

Question 2

what is meant by the term homologous series

Answer 2

a series of compounds with the same general formula, similar chemical properties, a trend in physical properties and the same functional group

Question 3

what is a functional group

Answer 3

a group of atoms that determines how a compound typically reacts

Question 4

define isomerism

Answer 4

molecules with the same molecular formula but different arrangement of atoms

Question 5

name the stem for organic compounds with 1-6 carbons

Answer 5

meth, eth, prop, but, pent, hex

Question 6

what is crude oil

Answer 6

a mixture of hydrocarbons

Question 7

describe the industrial process of fractional distillation

Answer 7

1) crude oil heated until vapourised then enters fractionating column
2) column is hot at bottom and cold at top
3) when the hydrocarbons reach the temperature lower than their boiling point they condense and are drained off
4) the longer hydrocarbons have higher boiling points so they condense at the bottom
5) the shorter hydrocarbons have lower boiling points so they condense at the top

Question 8

bitumen: uses + number of carbons

Answer 8

road surfaces

70+

Question 9

fuel oil: uses + number of carbons

Answer 9

large ship fuel

-40

Question 10

diesel: uses + number of carbons

Answer 10

cars/ large vehicles

-20

Question 11

kerosene: uses + number of carbons

Answer 11

aircraft fuel

-15

Question 12

gasoline: uses + number of carbons

Answer 12

car fuel

-8

Question 13

refinery gases: uses + number of carbons

Answer 13

domestic cooking/heating

-3

Question 14

what are the trends in physical properties in hydrocarbons

Answer 14

1) get more viscous/ thick as they get longer
2) get darker as they get longer
3) boiling point increases as they get longer

Question 15

what is a fuel

Answer 15

releases heat when burned

Question 16

products of incomplete combustion

Answer 16

carbon monoxide, soot (and C02, H20)

Question 17

complete combustion of hydrocarbons

Answer 17

hydrocarbon + oxygen -> C02+ H20

Question 18

why is carbon monoxide poisonous

Answer 18

binds with red blood cells and stops them carrying oxygen around the body; lack of oxygen leads to fainting, coma or death

Question 19

how is acid rain caused (by nitrogen oxide)

Answer 19

in car engines, the temperature is high enough for nitrogen to react with oxygen in the air, forming nitrogen monoxide
nitrogen monoxide reacts with oxygen in the atmosphere to make nitrogen dioxide
nitrogen dioxide dissolves in rain to form dilute nitric acid

Question 20

how is acid rain caused (by sulfur dioxide)

Answer 20

hydrogen fuels contain sulfur impurities
when these fuels are burnt, sulfut dioxide is formed
SO2 mixes with water vapour to form dilute sulfic acid

Question 21

what is cracking

Answer 21

splitting up longer chain alkanes into alkenes and shorter chain alkanes

Question 22

what conditions are needed for cracking

Answer 22

600-700 degrees

silica or alumina catalyst

Question 23

what is the general formula for alkanes

Answer 23

Cn H(2n+2)

Question 24

what is the general formula for alkenes

Answer 24

Cn H2n

Question 25

why are alkanes saturated hydrocarbons

Answer 25

they have the maximum number of H-C bonds (no double bonds) and only contain H and C

Question 26

describe the reactions of alkanes with halogens in the presence of UV radiation

Answer 26

a hydrogen atom from the alkane is substituted for a halogen so these are SUBSTITUTION reactions eg methane + bromine ->bromomethane + hydrogen bromide

Question 27

what is the functional group for alkenes

Answer 27

C=C

Question 28

why are alkenes unsaturated

Answer 28

they have a double bond

Question 29

describe the reactions of alkenes with bromine to make dibromoalkanes

Answer 29

- double bond broken and a bromine atom is added to each of the carbons - orange bromine water goes colourless

Question 30

how do you distinguish between alkenes and alkanes experimentally

Answer 30

shake with bromine water: alkene- goes colourless alkane- no change

Question 31

how are addition polymers formed

Answer 31

joining up many small molecules called monomers

Question 32

explain the problems in the disposal of addition polymers

Answer 32

1) inertness means they are hard to break down so won't biodegrade 2) produce toxic gases when burnt

Question 33

What makes a good fuel:

Answer 33

Releases a lot of heat energy (j/kg) Safe to use and convenient to store Reasonably cheap and easy to find Not produce toxic gases

Question 34

What are the problems with petrol

Answer 34

Disadvantages of using petrol: Produces CO2 (greenhouse gas) Not reusable Can produce harmful gases like carbon monoxide

Question 35

properties of polyethene

Answer 35

cheap, flexible, can be made into thin films

Question 36

properties of PVC

Answer 36

tough, electrical insulator, can be made hard or flexible

Question 37

properties of PFTE

Answer 37

slippery, unreactive

Question 38

how does limestone reduce acid rain

Answer 38

calcium carbonate (from limestone) -acidic gas passed through calcium carbonate in chimney -(calcium carbonate) neutralises/reacts with acidic gases - acidic gases prevented from entering the atmosphere

Question 39

Functional group of alcohols

Answer 39

O-H

Question 40

How can ethanol be oxidised

Answer 40

1) burning in air (complete combustion) 2) microbial oxidation 3) heating with potassium dichromate in dilute sulfuric acid

Question 41

What are the reactants and products of complete combustion of alcohols

Answer 41

Alcohol + oxygen -> C02 + H20

Question 42

What is microbial oxidation

Answer 42

Microorganisms use alcohols as an energy source They oxidise alcohols Carboxylic acids are made as a bi-product

Question 43

What happens when ethanol is heated with acidified potassium dichromate

Answer 43

Ethanol -> ethanoic acid H H H H-C-C-O-H ————> H-C-C=O H H H `OH ( heat needed)

Question 44

How can ethanol be manufactured (using steam)

Answer 44

``` Ethene reacts with steam to produce ethanol This is an addition reaction Conditions needed: 300 degrees 60-70 atm Phosphoric acid used as a catalyst ```

Question 45

How can ethanol be produced by fermentation

Answer 45

``` Glucose ———-> ethanol + C02 Yeast cells contain enzymes which catalyse this reaction Conditions 30 degrees c Anaerobic ```

Question 46

Functional group of carboxylic acids

Answer 46

-COOH

Question 47

Describe the reaction of carboxylic acids with metals

Answer 47

Carboxylic acid + metal -> salt + hydrogen

Question 48

Carboxylic acid reaction with Metal carbonate

Answer 48

Carboxylic acid + metal carbonate -> salt + water + C02

Question 49

What is vinegar

Answer 49

Ethanoic acid dissolved in water

Question 50

Functional group of esters

Answer 50

COO

Question 51

What ester is produced from ethanol and ethanoic acid

Answer 51

Ethyl ethanoate | Ethanol + ethanoic acid -> ethyl ethanoate + water

Question 52

What catalyst is used when forming esters

Answer 52

Acid catalyst (eg concentrated sulfuric acid)

Question 53

Word equation for the formation of an ester

Answer 53

Alcohol + carboxylic acid -> ester + water

Question 54

Practical: make an ester

Answer 54

1) add a few drops of concentrated H2SO4 in a boiling tube using a Pipette 2) add 10 drops of ethanoic acid 3) add 10 drops ethanol 4) place boiling tube in beaker of water on tripod 5) Heat using Bunsen Burner until water starts to boil 6) after 1 minute remove tube and cool 7) pour into test tube of sodium carbonate solution+mix 8) a layer of ester should form on top

Question 55

Describe condensation polymerisation

Answer 55

Polyester formed when dicarboxylic acid monomers and idol monomers react together

Question 56

What are biopolyesters

Answer 56

Biodegradable polyesters Can be broken down by living organisms Decompose so reduce pollutant effect