Production of Materials 1-1.4

Question 1

What are fossil fuels and what are they used for?

Answer 1

• Energy rich substances that are formed in the Earth’s crust millions of years ago from decomposing animal and plant matter.
• Used to provide energy requirements for machinery, produce other forms of energy, produce complex materials with various uses.

Question 2

How is petroleum formed?

Answer 2

• Under intense heat and pressure, the remains of marine organisms are gradually converted into petroleum.

Question 3

What is ethylene

Answer 3

(aka ethene) C2H4 is the simplest of the Alkene Homologous series. Saturated HC.

Question 4

What is the process of fractional distillation

Answer 4

Separation of a liquid mixture into fractions based on different boiling points.
Each fraction will contain molecules of similar molecular weight.
1. crude oil is preheated before entering F.C
2. In the F.C there are many bubble caps on large trays which allow separation.
3. The most volatile components bubble through the caps and rise higher where it is cooler.
4. compounds separate as they go up due to different Bp ranges.
5. Fractions are drawn off at different levels to produce a variety of different compounds.

Question 5

What is petroleum?

Answer 5

naturally occurring mixture of up to 300 HC as well as S and N compounds (usually crude oil but also natural gas)

Question 6

How is ethene made

Answer 6

ethene doesn’t occur naturally so it must be made from other chemcials within petroleum and natural gas.
Physical and chemical changes can be used to separate out compounds and convert them into simpler molecules.
Fractional distillation produces fraction of 18-25C atoms/chain which ethene is manufactured from by thermal cracking.

Question 7

what is cracking?

Answer 7

an endothermic process involving the breaking of covalent bonds of less useful longer chained HC to produce smaller chain alkanes and alkenes which are more useful.

Question 8

describe the 2 types of cracking

Answer 8

THERMAL: heating heavier fractions @ very high temps (900C)
CATALYTIC: powdered zeolite catalyst (an Al silicate with attached metal ions) is used inside a cat cracker. Catalyst has an open cage like crystalline structure with high internal S.A on which the cracking process occurs. Catalyst allows energy saving as process occurs at lower temps (500C)

Question 9

Equation of feedstocks to produce ethylene

Answer 9

C2H6 (g) –> C2H4 (g) + H2 (g)

C3H8 (g) –> C2H4 (g) + CH4 (g)

Question 10

Equation for alkanes, alkenes and alkynes

Answer 10

Alkanes are saturated HC (contain only H and C atoms)
CnH2n+2
Alkenes are unsaturated HC (contain at least 1 C-C double bond) CnH2n
Alkynes are unsaturated HC (contain at least one C-C triple bond) CnH2n-2

Question 11

Saturation

Answer 11

Unsaturated HC are fairly reactive due to their double bond

Saturated HC are inert

Question 12

What is a homologous series

Answer 12

group of compounds with similar structure and chemical properties (e.g. meth, eth)

Question 13

what is a functional group

Answer 13

a grouping of atoms that is common to all members of that series. (ending of name indicates functional group e.g. ane –> alkanes)

Question 14

C1-8 name

Answer 14

1 meth , 2 eth, 3 prop, 4 but, 5 pent, 6 hex, 7 hep, 8 oct

Question 15

Why is ethylene a useful starting point for producing industrial chemicals

Answer 15

the double bond in Ethylene allows it to react quickly and easily with other molecules.

Question 16

Addition reactions

Answer 16

ALKENES ONLY
One of the bonds in the double bond breaks open and an atom is added to (bonded) with each of the C atoms.
E.g. C2H4 (g) + HCl (l) –> C2H5Cl(aq)
ethene + Hydrogen chloride –> chloroethane

Question 17

Oxidation of ethanol

Answer 17

ethanol is converted to ethanal (acetaldehyde) and acetic acid
CH3CH2OH –> CH3CHO –> CH3COOH (O2 is used as a catalyst)
Ethanal used in perfumes and flavours. Acetic acid used in food manufacturing such as vinegar.

Question 18

Substitution reactions

Answer 18

(single displacement reaction)
ALKANES ONLY
atom is substituted for another already in the molecule. Requires light energy (UV light). One functional group is replaced by another functional group.
e.g. ethane + chloride gas –> chloroethane + HCl

Question 19

Reactivity and saturation

Answer 19

Unsaturated HC (alkenes) are reactive. Saturated HC are not.

Question 20

Bromine water test

Answer 20

• Bromine dissolved in H2O forms an equilibrium mixture of hypobromous acid.
  Br2 + H20 H+ + Br - +HOBR
  Alkenes will undergo an addition reaction and colour change from dark brown to colourless.
  CH2CH2 +HOBr –> CH2BRCH2OH (2-Bromoethanol)
  As HOBr is removed, more Br2 reacts with the water so its colour fades.
  Alkanes will undergo a substitution reaction which is very slow and no colour change will occur (stay brown)