DF 3 (prep yourself)

Question 1

what are petrol and diesel mixtures of

Answer 1

complex mixtures of many different compounds carefully blended to give the right properties
compounds obtained from crude oil

Question 2

what is crude oil and its physical state

Answer 2

its a mixture of many hundreds of hydrocarbons
its a thick back liquid with dissolved gases and solids

Question 3

how are the sources of petrol components obtained from crude oil

Answer 3

-oil from the north sea pumped to UK refineries
-crude oil heated to vaporise, then passed into distillation column
-separated into fractions, with certain ranges of boiling points
-gasoline and gas oil fractions are sources for festival components

Question 4

why do fractions not have exact boiling points

Answer 4

because they are mixtures of many different hydrocarbons

Question 5

what does organic chemistry entail and why

Answer 5

includes all carbon compounds because many carbon compounds are found in living organisms
-except carbon monoxide, carbon dioxide and the carbonates

Question 6

why do the properties of carbon make it so important

Answer 6

-first element of group 4, so it has 4 electrons in its outer shell, must lose or gain 4 electrons to be stable, but the charge would be too high
-so it forms covalent bonds instead
-forms strong covalent bonds with itself to form C-C covalent bonds (catenation)
-can form limitless variety of organic compounds

Question 7

what is a hydrocarbon

Answer 7

-compounds containing ONLY hydrogen and carbon

Question 8

what is an aromatic compound

Answer 8

compound that contains one or more benzene rings

Question 9

hat is an aliphatic compound

Answer 9

compounds that don’t contain benzene rings

Question 10

what is a functional group

Answer 10

modifiers that are responsible for the characteristic chemical reactions of molecules

Question 11

name the formula, shape and type of compound of the following compounds
-benzene
-methane
-cyclohexane
-ethene

Answer 11

BENZENE C6H6
-circle surrounded by hexagon
-arene

METHANE CH4
-carbon surrounded by 4 hydrogens (cross like) of single bonds
-alkane

CYCLOHEXANE C6H12
-hexagon
-cycloalkane

ETHENE C2H4
-carbon double bond, 2 diagonal hydrogens on each carbon
-alkene

Question 12

why does the benzene have the ring in the middle

Answer 12

each carbon in the hexagon of carbons makes three bonds and leaves one delocalised electron each in the centre to form a ring of them

Question 13

how do hydrocarbons, specifically alkanes and arenes become reactive

Answer 13

they are unreactive frameworks of hydrocarbons
modifiers
when other groups are attached the properties are modified
modifiers are also known as the functional group

Question 14

what is an alkane and describe the properties e.g formula

Answer 14

saturated hydrocarbons, so they contain the maximum number of hydrogen atoms possible without any carbon double or triple bonds
-formula Cn H 2n+2
-cracked to form alkenes
-they can be branched
-react with oxygen to make CO2 and 02
-can be isomerised

Question 15

what is a homologous series

Answer 15

a series of compounds in which all members have the same general formula and functional group
they all have similar chemical properties but different physical properties e.g melting and boiling points and density

Question 16

what is the molecular, full structural, shortened structural and further shortened formula of ethane

Answer 16

molecular formula: C2H6
full structural 2 carbons each attached to 3 hydrogens (up, down, left, right) by single bonds
shortened structural formula: CH3-CH3
further shortened: CH3CH3

Question 17

what is a structural isomer

Answer 17

when two compounds have the same molecular formula and a different structural isomer

Question 18

name the first 6 alkyl groups

Answer 18

CH3 methyl
CH3 CH2 ethyl
CH3 CH2 CH2 propyl
CH3 CH2 CH2 CH2 butyl
CH3 CH2 CH2 CH2 CH2 pentyl

Question 19

what are cycloalkanes

Answer 19

alkanes in a cyclic structure that are saturated

Question 20

state the molecular formula of cyclobutane and cyclohexane

Answer 20

cyclobutane - C4H8
cyclohexane- C6H12

Question 21

how to name branched alkanes

Answer 21

1. find the LONGEST chain e.g. hexane
2. identify the side chains e.g. butyl
   3.state the location of the side chain by the numbered carbon on the longest chain, trying to make the carbon number as low as possible
   e.g. 2-butylhexane
3. if there’s more than one side chain, keep numbers low as possible still and put them in alphabetical order
4. name the location of the side chains first with commas in between the no. s
   e.g 2,2-dimethyl propane

Question 22

describe the physical state of the first few alkanes

Answer 22

-first four of the series are colourless gases
-numbers 5-16 are colourless liquids
- numbers 17+ are white waxy solids

Question 23

how do alkanes mix with each other and water (why)

Answer 23

• mix well with each other
  -do not mix well with water, form two separate layers because alkanes contain non polar molecules but water contains polar molecules which attract each other and prevents the alkanes molecules mixing with them