Ammonia + Organic Chem

Question 1

Extraction of reactants

Answer 1

Nitrogen: Fractional distillation of liquid air

Hydrogen: Cracking of crude oil fractions.

Question 2

Conditions for Haber Process

Answer 2

1. 450 •C
2. 200 atm
3. Finely divided iron - Catalyst

Question 3

Why need the conditions?

Answer 3

Nitrogen molecules are generally unreactive.

Question 4

Why 200 atm?

Answer 4

Compromise pressure chosen on economic grounds. If the pressure used is too high, cost of generating ammonia exceeds the price you can get for the extra ammonia produced.

Question 5

Why 450•C?

Answer 5

When temperature is lower, POE shifts to the right to produce more heat. Hence, the lower the temperature, the higher the yield. However, a lower temperature also results in a slower reaction. Hence, a relatively higher temperature of 450•C is used as a compromise.

Question 6

Why finely divided?

Answer 6

Increased surface area to speed up reaction.

Question 7

Why recycle reactants?

Answer 7

1. Saving cost
2. Conserve finite resources - Hydrogen comes from cracking crude oil
3. Conserve energy needed to obtain raw materials
4. Increase yield of ammonia- prevent wastage of reactants

Question 8

Drying agent for ammonia

Answer 8

Calcium oxide. Concentrated sulfuric acid and calcium chloride cannot be use as they are acidic and reacts with ammonia.

Question 9

Cracking of petroleum(crude oil)

Answer 9

1. Fractional distillation is used to separate petroleum as the fractions in petroleum have different boiling points.
2. Petroleum is heated in the furnace to become a vapour.
3. Petroleum vapour passes up the fractioning column, fractions condense out of the column at different heights depending on their boiling points.
4. Lighter fractions have lower boiling points, they come out as fractions near the top of the column. Heavier fractions have higher boiling point, they come out as fractions at the lower sections of the column.

Question 10

Why separate petroleum?

Answer 10

Petroleum contains a large mixture of hydrocarbons of varying length. Thus, it will be a less efficient fuel, resulting in sootier and smokier flame when burnt.

Question 11

Fractions

Answer 11

1. They are a range of varying length of hydrocarbons.

2. They have a range of boiling point.

Question 12

Use of fractions

Answer 12

Petroleum gas: Fuel for cooking/ heating
Petrol: fuel for car engines
Naphtha: used as chemical feedstock for chemical industries
Kerosene/paraffin: fuel for aircraft engine or fuel for domestic cooking + heating
Diesel: fuel for diesel engines
Lubricating oil: lubricant for machines, sources of waxes and polishes
Bitumen: making road surfaces

Question 13

Issues with use of petroleum

Answer 13

Pollution and global warming

Non-renewable and finite

Question 14

Ways to conserve petroleum

Answer 14

1. Reduce the use of petroleum
2. Use alternative energy sources
3. Increase efficiency

Question 15

Organic compounds

Answer 15

Contains the element carbon. Most contain hydrogen.

Question 16

Hydrocarbons

Answer 16

Organic compounds that contain carbon and hydrogen only.

Question 17

Homologous series

Answer 17

Homologous series is a family of organic compounds with the same functional group and similar chemical properties

Question 18

Functional group

Answer 18

An atom or group of atoms that give a molecule its characteristic chemical properties.

Question 19

Characteristics of Organic compounds of same homologous series

Answer 19

1. Same general formula
2. Similar chemical properties - same functional group
3. Differ from successive member by a CH2 group
4. There is a gradual change in their physical properties

Question 20

Trends in physical properties

Answer 20

1. Melting point and boiling point increases.

Molecular sizes increases, number of electrons increases, strength of intermolecular forces of attraction between the molecules increases, higher energy required to overcome the intermolecular forces of attraction.

2. Viscosity increases.
   Molecular sizes increases, number of electrons increases, strength of intermolecular forces of attraction between the molecules increases, flow less easily.
3. Less flammable.

Molecular sizes increases, number of electrons increases, strength of intermolecular forces of attraction between the molecules increases, higher energy required to overcome the intermolecular forces of attraction, higher bp and less volatile and less flammable.

Question 21

Name of homologous series

Answer 21

Alkane- no FG, -ane
Alkene- C=C, -ene
Alkyne- C [triple bond] C, -yne
Halogenoalkane- -X, X-+-ane
Alcohol- -O-H, -ol
Aldehyde- -C=O-H, -al
Ketone, =O, -one
Carboxylic acid, =O-OH, -oic acid
Ester, -O-O-, -oate

Question 22

Parent

Answer 22

According to number of C atoms in the longest continuous carbon chain.

Meth-
Eth-
Prop-
But-
Pent-
Hex-
Hept-
Oct-
Non-
Dec-

Question 23

Suffix

Answer 23

Indicate the functional group.

Question 24

Prefix

Answer 24

Denotes or other substituent groups.

Chloro
Bromo
Iodo