Alkanes

Question 1

Define hydrocarbon.

Answer 1

A compound made up of only hydrogen and carbon atoms.

Question 2

Describe: empirical, molecular, general, structural, displayed and skeletal formulae.

Answer 2

Lowest whole number ratio
Actual number of atoms
Algebra representation for any chain in homologous series
Shows arrangement of atoms
Shows all bonds

Question 3

Homologous series definition

Answer 3

A series of organic compounds with the same functional group and similar chemical properties

Question 4

Define functional group

Answer 4

A specific grouping of atoms with their own characteristic properties, regardless of the other atoms present in the molecule

Question 5

What is chain isomerism

Answer 5

Carbon skeleton can be arranged differently. Straight chain or or branches . Similar chemical properties, different physical properties.

Question 6

What is positional isomerism

Answer 6

Functional group bonded to different carbon atoms on same chain. Different physical properties and maybe different chemical properties.

Question 7

What is functional group isomerism

Answer 7

Same atoms arranged into a different functional group. Can have very different chemical and physical properties.

Question 8

Definition of saturated carbon

Answer 8

All atoms are bonded by single bonds

Question 9

What are the main stages used to obtain Alkane fuels

Answer 9

Fractional distillation
Cracking
reforming

Question 10

What is a radical and how is it represented

Answer 10

A species with unpaired electron formed by homolytic fission of a covalent bond
Represented by in mechanism by single dot

Question 11

Products of combustion of alkanes

Answer 11

Carbon dioxide and water

Question 12

what are the three steps of free radical substitution

Answer 12

initiation: diatomic molecule into two free radicals
propagation: radical reacts with non radical to form new radical and product.
termination: two radicals react to form different products

Question 13

what are the limitations of the use of free radical substitution

Answer 13

further substitution reactions occur.

forms a mixture of products.

Question 14

what are the products from a reaction between an alkane and a halogen with UV light

Answer 14

haloalkane

hydrogen halide

Question 15

what is the trend in volatility for alkanes

Answer 15

longer chains means lower volatility as there are more london forces.
staighter chain decreaces volatility because of the larger contact surface area.

Question 16

why are alkanes relatively inert

Answer 16

they are fully saturated

Question 17

what is reforming

Answer 17

the processing of straight chain hydrocarbons being turned into branched chain alkanes or cycloalkanes for efficient combustion

Question 18

what is the order of fractions from crude oil, bottom to top

Answer 18

residue (bitumen)
gas oil (diesel)
kerosine (jet fuel)
naphtha (reformed into gasoline)
gasolines (petrol)
gases (refinery gas)

Question 19

what are the conditions for catalytic cracking

Answer 19

pass hydrocarbon over steam and silica catalyst and alumina catalyst. 450 degree C. no oxygen

Question 20

what are the three types of reforming

Answer 20

isomerisation
cyclisation (cycloalkane and hydrogen)
aromatisation

Question 21

what are the harmful bi products of combustion of alkanes

Answer 21

carbon monoxide
sulfur di and trioxide
nitrogen mon and dioxide

Question 22

how do catalytic converters work

Answer 22

high surface area and platinum catalyst.

2NO+2CO->N2+2CO2