Chapter 17-Organic Chemistry

Question 1

Define:

Hydrocarbon

Answer 1

A compound made of only Hydrogen and Carbon.

Question 2

Define:

Homologus Series

Answer 2

A series of compounds with the same general formula and functional group. They have similar properties.

Question 3

Name 2 properties of Alkanes.

Answer 3

• The all end with the name -ane
• They have the general formula: C_n H_2n+2
• Saturated, no spare bonds.

Question 4

Describe what happens as you go down the Alkanes.

Answer 4

• Boiling points increase
• Less volatile
• Harder to ignite
• As you go down: Gas-Liquid-Solid

Question 5

Think: Combustion (Complete + Incomplete) and Chlorine

Describe 3 reactions which Alkanes undergo.

Answer 5

1. Complete (lots O₂) Alkane (i.e. Methane) + Oxygen > Carbon Dioxide + Water.
2. Incomplete (few O₂) Alkane (i.e. Methane) + Oxygen > Carbon Monoxide + Water
3. Chlorine *(photochemical)* Alkane (i.e. Methane) + Chlorine > Chloroalkane (Chloromethane**) + Hydrogen Chloride.

Question 6

Name 3 properties of Alkenes.

Answer 6

1. General Formula: C_nH_2n
2. Names end in -ene
3. C=C, spare (double) bond so unsaturated and more reacitve.

Question 7

Describe what happens as you go down the alkene chain.

Answer 7

1. Boiling points increase
2. More viscous
3. Less volatile

Question 8

How are alkenes made?

Answer 8

Through a porcess called cracking, this involves heat.

Alkane > Alkene + Hydrogen

Question 9

Describe the 3 reactions which alkenes undergo.

Answer 9

1. Alkene (i.e. Ethene) + Hydrogen >_{Heat, Pressure, Catalyst} > Alkane (i.e. Ethane)
2. (Reversible) Alkene (i.e. Ethene) + Water >_{Heat, Pressure, Catalyst}< Alcohol (i.e. Ethanol)
3. Polymerisation-consists of long chains of monomers joined up.

Question 10

How does one differentiate an alkene from an alkane.

Answer 10

React them in Bromine Water.

• The alkane is unreactive as it has full bonds, so Bromine Water remains brown/orange.
• The alkene is reactive as it has spare (double) bonds, so Bromin Water goes from brown/orange to colourless.

Question 11

Name 3 properties of Alcohols.

Answer 11

1. Contain the functional group OH, this means they react in the same way.
2. Names end in -ol
3. General formula: C_nH_2n+1OH

Question 12

Why are alcohols like Ethanol important?

Answer 12

• Ethanol is used in alcoholic drinks
• It’s a good solvent, dissolves things water can’t.
• Evaporates easily-very volatile, makes it suitable for perfumes, glue, printer inks, etc.

Question 13

Name 2 properties of Carboxylic Acids.

Answer 13

1. They have the general formula: C_nH_2nO₂
2. Have the functional group COOH (OH-C=O)

Question 14

What are esters?

Answer 14

Esters are formed when an alcohol and a carboxylic acid react.

Reactions are reversible, and sulfuric acid acts as a catalyst.

Question 15

Why is the formation of esters a condensation reaction?

Answer 15

Because not only does it give off water but two molecues reacted giving off a large molecule and a small molecule.

Question 16

Define

Cracking

Answer 16

Process of breaking down large molecule into smaller ones via thermal decomposition.

Question 17

How is petroleum (crude oil) seperated?

Answer 17

Through fractional distillation.

Question 18

List the different number of fractions into which petroleum is seperated into, and their uses.

Answer 18