Section 3: Organic Chemistry

Question 1

What is a homologous series?

Answer 1

Compounds in the same homologous series have the same general formula and similar chemical properties.

Question 2

What is a hydrocarbon?

Answer 2

A compound containing only hydrogen and carbon

Question 3

What does saturated mean?

Answer 3

A saturated atom has bonded as many times as possible.

Question 4

What does unsaturated mean?

Answer 4

An unsaturated atom can bond more times.

Question 5

What is the general formula?

Answer 5

The most simplified the ratio of molecules can be

Question 6

What is isomerism?

Answer 6

Isomers have the same molecular formula, but different displayed formulas (structure).

Question 7

What is the general formula of an alkane?

Answer 7

CnH2n+2

Question 8

What are the first five straight-chain alkanes?

Answer 8

methane, ethane, propane, butane, pentane

Question 9

What are the products of the complete combustion of alkanes?

Answer 9

carbon dioxide and water

Question 10

What are the products of the incomplete combustion of alkanes?

Answer 10

carbon monoxide and water

Question 11

Describe the substitution reaction of methane and bromine.

Answer 11

Under UV light, bromine and methane will form bromomethane.
CH4 + Br2 –> CH3Br + HBr
This is a substitution reaction because bromine has taken the place of the hydrogen atom.

Question 12

What is the general formula of an alkene?

Answer 12

CnH2n

Question 13

What are the first four straight-chain alkenes?

Answer 13

ethene, propene, butene, pentene

Question 14

Describe the addition reaction of alkenes with bromine.

Answer 14

An alkene will make its double bond into a single bond, to bond to two bromines. Bromine is added to the molecule. The product made is colourless. If you add alkenes to bromine water, it will turn colourless, as it reacts with the alkenes.

Question 15

Describe the manufacture of ethanol by using ethene and steam.

Answer 15

C2H4 + H2O –> C2H5OH

Phosphoric acid catalyst, temperature of 300 degrees C, and pressure of 60-70atm

Question 16

Describe the manufacture of ethanol by the fermentation of sugars

Answer 16

Ethanol can be made by the anaerobic respiration of microorganisms.
glucose –> ethanol + carbon dioxide
This happens at 30 degrees.

Question 17

Evaluate the manufacture of ethanol by hydration of ethene

Answer 17

Crude oil (cracked to make ethene) expensive/ non-renewable
Fast process
Pure product
Continuous reaction

Question 18

Evaluate the manufacture of ethanol by fermentation

Answer 18

Cane sugar widely available/ cheap/ renewable
Slow process
Impurities in the product
Done in batches

Question 19

Describe the dehydration of ethanol to ethene using aluminium oxide

Answer 19

C2H5OH > C2H4 + H2O

aluminium oxide is the catalyst for this reaction.