Topic 7: organic chemistry

Question 1

what is crude oil

Answer 1

crude oil is a mixture of compounds; a fossil fuel consisting of the remains of ancient biomass

Question 2

what is a finite resource

Answer 2

cannot be replaced as it it is used up

Question 3

what is a hydrocarbon

Answer 3

a compound made up exclusively of hydrogen and carbon atoms

Question 4

what are alkanes

Answer 4

saturated hydrocarbons of a general formula

Question 5

what is a homologous series

Answer 5

a series of compounds with same general formula, same functional groups and similar chemical properties

Question 6

describe the combustion of hydrocarbons

Answer 6

• exothermic reaction occurring when hydrocarbons are reacted with oxygen
• complete combustion produces carbon dioxide and water
• incomplete combustion produces carbon and carbon monoxide + water

Question 7

describe the physical properties of alkanes

Answer 7

• first few in series are gases, then change to liquids, then to solids
• in general, boiling points and viscosity increase as molecules get bigger
• volatility and flammability decrease as molecules get bigger
• poor reactivity

Question 8

explain how fractional distillation of crude oil takes place

Answer 8

• crude oil is heated and vaporised
• vapour rises up the fractional column
• the column is hotter at the bottom and cooler at the top
• hydrocarbons cool as they go up the column and condense at different heights, as they have different boiling points
• large molecules, high boiling points, collected at the bottom
• small molecules, low boiling points, collected at the top
• this gives fractions, which can be used in various ways

Question 9

what is cracking

Answer 9

when large hydrocarbons are thermally broken down into smaller and useful molecules

Question 10

what type of reaction is cracking

Answer 10

thermal decomposition

Question 11

what are the conditions for cracking

Answer 11

reactant heater to vapour, passed over a hot catalyst or heated to vapour, mixed with steam and heated to high temperatures

Question 12

how are the products of cracking used

Answer 12

the products are alkanes and alkenes - used as polymers and starting materials for synthesis

Question 13

what is an alkene

Answer 13

an unsaturated hydrocarbon

Question 14

what bond do an alkene have

Answer 14

c=c bond

Question 15

what is the general formula for alkenes

Answer 15

CnH2n

Question 16

what is the test of alkenes

Answer 16

add bromine water
colour change occurs from orange to colourless

Question 17

describe the combustion of alkenes

Answer 17

they burn with smoky flames due to incomplete combustion

Question 18

what is an alcohol
(not the drink)

Answer 18

an organic compound that contains an -OH functional group

Question 19

state characteristics of methanol, ethanol, propanol, butanol

Answer 19

• dissolve in water to form a neutral solution
• react with sodium to from hydrogen
• burn in oxygen
• react with carboxylic acids in presence of acid catalysts to form esters

Question 20

oxidation of the alcohols lead too

Answer 20

carboxylic acids

Question 21

some uses of alcohols

Answer 21

fuels
solvents
drinks

Question 22

state the conditions required for fermentation of glucose

Answer 22

30 degrees celsius
aqueous solution of glucose
absence of air
yeast is added

Question 23

what are carboxylic acids

Answer 23

organic compounds that contain a COOH functional group

Question 24

state characteristics of carboxylic acids

Answer 24

• dissolve in water to form an acidic solution
• react with metal carbonates to form carbon dioxide
• react with alcohols with an acid catalyst to produce esters
• react with metals to give off hydrocarbon gas

Question 25

what type of acid is carbonic acid?

Answer 25

it is a weak acid

Question 26

explain why carboxylic acids are weak acids

Answer 26

they are partially dissociated in water, thus the Ph of carboxylic acid in the solution is not as low as a solution of a strong acid of the same concentration

Question 27

what is an ester and how is it formed?

Answer 27

an organic compound containing a -COO- functional group, formed from carboxylic acid and alcohol in the presence of a sulphuric acid catalyst they have a fruity smell

Question 28

what is a polymer

Answer 28

a polymer is a long chain molecule which is made by lots of smilier molecules joining together

Question 29

how do molecules contain c=c bonds form polymers

Answer 29

c=c bonds open up and many smaller molecules (monomers) join together to form a chain. no other products are made it is called an addition polymerisation reaction

Question 30

3 examples of addition polymers and their uses

Answer 30

polythene - plastic bag polytetaflurioethen - teflon surfaces, for use on non-stick kitchenware polychloroethene - water pipes

Question 31

what is a repeating unit of a polymer

Answer 31

it is a smallest structure which, upon numerous translations, yields the structure of the polymer

Question 32

what is a condensation polymer

Answer 32

it is a polymer made up in condensation polymerisation in this reaction many molecules join together, the polymer is formed but also a small molecule is released

Question 33

what is amide bond

Answer 33

an amide bond is similar to the ester bond, it contains the c=o group

Question 34

what is amino acid

Answer 34

it is an organic compound that contains both a carboxylic acid functionality and an amine functional group

Question 35

how do amino acids make proteins

Answer 35

by numerous condensation polymerisation; protein are polymers made of amino acids

Question 36

what are polypeptides

Answer 36

polypeptides are also made by condensation polymerisation of amino acids, but are shorter than proteins. one could think about proteins as a product of many polypeptide chains bonded together

Question 37

what are carbohydrates

Answer 37

they are organic molecules made of C,H and O. they are basically relevant. both of these polymers made of glucose monomers, their structures differ in the way the glucose molecules are joined together.

Question 38

what does DNA stand for

Answer 38

DNA is deoxyribonucleic acid

Question 39

what is DNA

Answer 39

dna is a material that makes up chromosomes, cell structures that store genetic information dna is made of two polymer chains that are held together in a double helix. each polymer chain can be made from 4 different monomers, nucleotides