Organic Chemistry

Question 1

Name the three fossil fuels.

Answer 1

coal, natural gas and petroleum

Question 2

What is the main constituent of natural gas?

Answer 2

methane

Question 3

Define the term ‘hydrocarbon’.

Answer 3

Compounds containing hydrogen and carbon only

Question 4

What process is used to separate petroleum into its fractions?

Answer 4

Fractional distillation

Question 5

What is petroleum?

Answer 5

a mixture of hydrocarbons

Question 6

What is a fraction?

Answer 6

a group of hydrocarbons with similar chain lengths

Question 7

What are features of fractions obtained from petroleum at the top of the fractionating column?

Answer 7

• lower boiling points - runny- volatile- smaller chain length

Question 8

What are features of fractions obtained from petroleum at the bottom of the fractionating column?

Answer 8

• higher boiling points- viscous- low volatility- bigger chain length

Question 9

What is the order of the fractions, from the smallest chain to the largest?

Answer 9

refinery gas, gasoline, naphtha, paraffin, diesel oil , fuel oil , lubricating fraction, bitumen

Question 10

What is the use of refinery gas?

Answer 10

heating and cooking

Question 11

What is the use of gasoline?

Answer 11

fuel in cars

Question 12

What is the use of naphtha?

Answer 12

chemical feedstock

Question 13

What is the use of paraffin?

Answer 13

jet fuel

Question 14

What is the use of diesel oil?

Answer 14

fuel used in diesel engines

Question 15

What is the use of fuel oil?

Answer 15

fuel in ships and home heating systems

Question 16

What is the use of lubricating oil?

Answer 16

for lubricants, waxes and polishes

Question 17

What is the use of bitumen?

Answer 17

making roads

Question 18

What is the general formula of alkanes?

Answer 18

CnH2n+2

Question 19

What is the general formula of alkenes?

Answer 19

CnH2n

Question 20

What is a functional group?

Answer 20

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

Question 21

What is a structural formula?

Answer 21

an unambiguous description of the way atoms in a molecule are arranged

Question 22

What are structural isomers?

Answer 22

compounds with the same molecular formula, but different structural formulae

Question 23

What is a homologous series?

Answer 23

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

Question 24

What is a saturated compound?

Answer 24

contains molecules containing only C-C single bonds

Question 25

What is an unsaturated compound?

Answer 25

contains molecules containing at least one C-C double + bond

Question 26

What are the general characteristics of a homologous series?

Answer 26

- have the same functional group- have the same general formula- trend in physical properties- similar chemical properties

Question 27

How is the bonding in alkanes?

Answer 27

single covalentsaturated hydrocarbons

Question 28

Are alkanes reactive or unreactive?

Answer 28

generally unreactive, except in combustion and with halogens in UV light

Question 29

What happens in a substitution reaction?

Answer 29

one atom/group of atoms is replaced by another atom/group of atoms

Question 30

What type of reaction is the reaction between alkanes and chlorine?

Answer 30

substitution + photochemical

Question 31

What is the condition necessary for alkanes to react with chlorine? Why?

Answer 31

UV light, it gives the activation energy

Question 32

How is the bonding in alkenes?

Answer 32

contains a covalent carbon-carbon double bondunsaturated hydrocarbons

Question 33

Why is cracking used?

Answer 33

-because long chain alkanes can be turned into more useful short chain alkanes (can be used for fuels)-alkenes produced can be used to make polymers (plastic)

Question 34

What happens when an alkene comes into contact with aqueous bromine? How does this differ from an alkane's reaction with aqueous bromine?

Answer 34

alkene - decolorises aqueous brominealkane - no difference

Question 35

How many products are formed in an addition reaction?

Answer 35

ONLY one

Question 36

What type of reaction do alkenes undergo?

Answer 36

addition

Question 37

What happens in a reaction between an alkene and hydrogen?

Answer 37

the product becomes an alkene, with the same number of carbon atoms than before but different number of hydrogen atoms

Question 38

What is necessary for an alkene to react with hydrogen?

Answer 38

nickel + 200ºC

Question 39

What happens when an alkene reacts with steam?

Answer 39

it forms an alcohol

Question 40

What is necessary for an alkene to react with steam?

Answer 40

300ºC + phosphoric acid

Question 41

What conditions are necessary for cracking?

Answer 41

high temperaturecatalyst - either ceramic or aluminium oxide

Question 42

What is produced in cracking?

Answer 42

shorter chain alkanes and alkenes (more useful)

Question 43

What type of reactions do alkanes undergo?

Answer 43

substitution reactions

Question 44

Which hydrocarbons are more volatile? At the top or bottom of the fractionating column?

Answer 44

more volatile if higher up the fractionating columnthe smaller the molecule, the more volatile

Question 45

State in order the prefixes of alkanes and alkenes according to the number of carbon atoms.

Answer 45

1. meth-2. eth-3. prop-4. but-5. pent-6. hex-7. hept-8. oct-

Question 46

Which hydrocarbons are more viscous? At the top or bottom of the fractionating column?

Answer 46

the larger the molecule, the more viscous

Question 47

word equation for combustion

Answer 47

fuel (hydrocarbon) + oxygen -> carbon dioxide + water

Question 48

word equation for combustion

Answer 48

fuel (hydrocarbon) + oxygen -> carbon dioxide + water

Question 49

what is combustion

Answer 49

burning

Question 50

when does incomplete combustion occur?

Answer 50

when there is a shortage of oxygen

Question 51

what is formed as result of incomplete combustion? Why is it dangerous?

Answer 51

carbon monoxide (colorless odorless gas) and/ or soot. carbon monoxide is dangerous as it binds irreversebly to haemoglobin, reducing its ability to carry oxygen

Question 52

what are the possibilities of products in cracking

Answer 52

- alkene + hydrogen- alkene + alkane- alkane + alkene + alkane

Question 53

word equation for incomplete combustion

Answer 53

fuel + oxygen -> carbon monoxide + water

Question 54

process of fractional distillation (so para annuca - mari ignora esse card)

Answer 54

- The boiling crude oil is transferred into a large fractioning column- The lighter gaseous hydrocarbon rises the column- When gaseous hydrocarbon rises the column, it starts to cool, and when the temperature reaches below boiling points, it is converted to a liquid state.