DF3: Hydrocarbons and Nomenclature

Question 1

What is crude oil?

Answer 1

A thick black liquid consisting of a mixture of hydrocarbons

Question 2

Explain the process of fractional distillation.(4)

Answer 2

• At the refinery, the crude oil is heated to vapourise it
• vapour passes into the distillation column
• Vapour rises up through the column, separating into different fractions
• as different ones condense into liquids and run off at different levels

Question 3

Does density increase/decrease up a fractionating column?

Answer 3

Decrease

Question 4

Does boiling point increase/decrease up a fractionating column?

Answer 4

Decrease

Question 5

Does chain length increase/decrease up a fractionating column?

Answer 5

Decrease

Question 6

Does volatility increase/decrease up a fractionating column?

Answer 6

Increase

Question 7

Does flammability increase/decrease up a fractionating column?

Answer 7

Increase

Question 8

Why does each fraction not have an exact boiling point?

Answer 8

Each one is a mixture of many different hydrocarbons

Question 9

What does organic chemistry include?

Answer 9

All carbon compounds except CO, CO2 and carbonates

Question 10

How many electrons does carbon have in its outershell?

Answer 10

4

Question 11

Why does carbon generally form covalent bonds?

Answer 11

If it achieved stability by becoming an ion it would be too highly charged (4+ or 4-)

Question 12

What does catenation lead to?

Answer 12

The limitless variety of organic compounds

Question 13

Define “hydrocarbon”

Answer 13

Compounds containing only carbon or hydrogen

Question 14

What is the general formula for hydrocarbons?

Answer 14

CxHy

Question 15

Define “aromatic”

Answer 15

Compounds containing one/more benzene rings

Question 16

Define “aliphatic”

Answer 16

Compounds not containing any benzene rings

Question 17

Define “functional group”

Answer 17

Modifiers responsible for the characteristic chemical reactions of molecules

Question 18

Define “saturated”

Answer 18

A compound with no bonds available for bonding

Question 19

Define “unsaturated”

Answer 19

A compound containing bonds that can be broken open

Question 20

Define “homologous series”

Answer 20

A series of compounds with the same general molecular formula

Question 21

Are alkanes saturated?

Answer 21

Yes

Question 22

How many bonds does carbon form?

Answer 22

4

Question 23

Are alkanes aliphatic?

Answer 23

Yes

Question 24

What is the general formula for alkanes?

Answer 24

CnH2n+2

Question 25

Name the first ten alkanes

Answer 25

- Methane - Ethane - Propane - Butane - Pentane - Hexane - Heptane - Octane - Nonane - Decane

Question 26

What is the relationship between alkane chain length and tendency to become a solid and why?

Answer 26

As chain length increases, the tendency towards a solid also increases because the boiling point increases

Question 27

What state are alkanes n= 1 - 4 in?

Answer 27

Colourless gases

Question 28

What state are alkanes n=5 - 16 in?

Answer 28

Colourless liquids

Question 29

What state are alkanes n=17+ in?

Answer 29

White waxy solids

Question 30

Do alkanes mix well with water?

Answer 30

No they form two separate layers

Question 31

Why do alkanes not mix well with water?

Answer 31

Water contains polar molecules that attract each other and prevent alkane molecules mixing with them

Question 32

What are cycloalkanes?

Answer 32

A ring of carbon atoms with two hydrogens attached to each carbon

Question 33

What is the general formula for alkanes?

Answer 33

CnH2n+2

Question 34

Are cycloalkanes saturated?

Answer 34

Yes

Question 35

Are alkenes saturated and why?

Answer 35

No - the carbon double bond can open up and bond with more hydrogens

Question 36

What is the general formula for alkenes?

Answer 36

CnH2n

Question 37

Are alkenes aliphatic?

Answer 37

Yes

Question 38

What is the general formula for cycloalkenes?

Answer 38

CnH2n-2

Question 39

Are cycloalkenes aliphatic?

Answer 39

Yes

Question 40

Are cycloalkenes saturated?

Answer 40

No

Question 41

Is alcohol a hydrocarbon?

Answer 41

No

Question 42

What is the general formula for alcohols?

Answer 42

CnH2n+1OH

Question 43

What is the functional group for alcohols?

Answer 43

The hydroxl group (-OH) which can be attached to any carbon atom on the chain

Question 44

What is a general formula?

Answer 44

A formula that can describe any member of a family of compounds

Question 45

What is a molecular formula?

Answer 45

The actual number of atoms of each element in a molecule

Question 46

What is the shortened structural formula?

Answer 46

A formula showing the atoms, carbon by carbon with the attached hydrogens and functional groups

Question 47

What is the structural formula?

Answer 47

Shows how all the atoms are arranged and all the bonds between them

Question 48

What is the skeletal formula?

Answer 48

Shows the bond between the carbon skeleton only, with any functional groups. The hydrogen and carbon atoms are not shown.

Question 49

Why is giving systematic names important?

Answer 49

It allows for the full structural formula of a compound to be determined.

Question 50

What is the formula of methyl?

Answer 50

-CH3

Question 51

What is the formula for all alkyls after methyl?

Answer 51

CH3 + CH2 for every carbon atom

Question 52

What is the prefix for two identical sidechains?

Answer 52

Di

Question 53

What is the prefix for three identical sidechains?

Answer 53

Tri

Question 54

What is the prefix for four identical sidechains?

Answer 54

Tetra