Organic Chemistry

Question 1

Homologous series

Answer 1

Same general formula
Similar chemical properties
Gradation in their physical properties
Differ by a CH2 unit

Question 2

What is a hydrocarbon

Answer 2

A compound/molecule consisting of hydrogen and carbon only

Question 3

Alkanes

Answer 3

General formula: CnH2n+2, at room temperature and pressure; all colourless gasses (meth/eth/propl/but - ane)

Question 4

Functional group

Answer 4

Reactive group in a molecule

Question 5

Complete Combustion (Alkanes)

Answer 5

Products: Carbon dioxide + Water + Heat. Test: For CO2, bubble combustion products through colourless lime water- becomes milky white -CO2 present, for H2O condense the vapour by cooling- add white anhydrous copper(II) sulfate - becomes blue (H2O present)

Question 6

Incomplete Combustion for alkanes

Answer 6

(Limited oxygen)Products: Carbon Monoxide + water

Question 7

Problems Carbon dioxide, carbon monoxide, soot, sulfur dioxide (leading to acid rain)

Answer 7

Carbon dioxide: Greenhouse gas- absorbs IR given off by the earth - causes earths surface to warm- sea level rises, flooding, climate change
Carbon monoxide: Toxic gas (as combines with haemoglobin in the blood- reducing capacity to carry oxygen)
Soot: Carbon particles pollute the air- causes lung damage and respiratory problems
Sulfur dioxide: Acid rain- damages buildings ( especially limestone ones), damages vegetation, kills fish in lakes and rivers

Question 8

Alkenes

Answer 8

General formula: CnH2n
Functional group: Carbon- Carbon double bond (C=C)
At room temp and pressure all colourless gases (eth/prop/but-1/but-2 ene)

Question 9

Complete combustion of Alkenes

Answer 9

Products- Carbon dioxide + Water ( burns with an orange flame)

Question 10

Incomplete combustion of Alkenes

Answer 10

(Limited oxygen) Products- carbon monoxide + water (sometimes soot, but don’t put in equation)

Question 11

Unsaturated

Answer 11

The molecule contains one or more carbon-carbon double bonds

Question 12

Addition reaction

Answer 12

Two molecules react to form one product

Question 13

Addition reaction of Alkenes with bromine

Answer 13

Bromine adds across the double bond
Condition: room temp
This reaction is to test for the presence of a C=C bond- If organic substance is a liquid- shake with bromine water. If a gas- bubble the gas into bromine water
Orange bromine water changes to colourless in presence of a C=C bond

Question 14

Addition reaction with Alkenes and hydrogen

Answer 14

Hydrogen adds across the C=C double bond
Conditions: Temperature 150 degrees Celsius, catalyst of nickel
Reaction called hydrogenation

Question 15

Addition reactions of Alkenes with steam

Answer 15

Called hydration as water is being added across the C=C double bond
Conditions: Catalyst and high temperatures

Question 16

What is a Polymer

Answer 16

Is a long chain molecule made from joining small molecules together

Question 17

What is a monomer

Answer 17

A small molecule that combines with other monomers to make a polymer

Question 18

What is Addition polymerisation

Answer 18

The process of joining monomer molecules together to form a long chain molecule

Question 19

Chemical equation to form poly(ethene) from ethene monomers

Answer 19

H. H. —H. H —
|. |. | |. | |
n C = C. —————> -— |- C. C -|—-
|. |. |. |. |. |
H. H. —H. H—. n

Question 20

Definition of a biodegradable material

Answer 20

A biodegradable material is one which is not decomposed by natural bacteria in the environment

Question 21

Advantages and disadvantages of Landfill and Incineration

Answer 21

Landfill- Advantages- cheap(waste transported to a local site/ not much money for transport).
Disadvantages- wastes land(used for building and agriculture) -eyesores causes visual pollution
Incineration- Advantages- Heat energy produced during incineration- can be used to generate electricity.
Disadvantages- polluting gases released(CO2- can cause global warming) - High costs to buy an incinerator

Question 22

Alcohols

Answer 22

General formula: CnH2n+1OH
Functional group- hydroxyl group(-OH)
At room temp and pressure- all colourless liquids (methanol/ethanol/propan-1-ol /propan-2-ol)

Question 23

Complete combustion of alcohols

Answer 23

Products- Carbon dioxide and water
Clean(non smoky) blue fame with an orange tip

Question 24

Incomplete combustion of alcohols

Answer 24

Limited oxygen products- carbon monoxide and water (and soot)

Question 25

Oxidation of alcohols by air

Answer 25

*Propan -2-ol can be oxidised but a carboxylic acid is not formed but methanol, ethanol, and propan -1-ol can be oxidised by air to form carboxylic acids

Question 26

Oxidation of alcohols by acidified potassium dichromate

Answer 26

This is an oxidising agent which oxidises some alcohols(methanol, ethanol, propan -1-ol) to carboxylic acids, on warming. Observations: Acidified potassium dichromate solution changes from orange to green Condition: warm in a water bath Propan -2-ol is the same but a carboxylic acid is not formed

Question 27

Fermentation and the conditions

Answer 27

The breakdown of sugars to produce ethanol and carbon dioxide Conditions - sugars are dissolved in solution - in the presence of yeast - at a warm temperature (not above 37 degrees Celsius) - in the absence of air

Question 28

Carboxylic Acid

Answer 28

Functional group: carboxyl (-COOH) At room temp and pressure all colorless liquids(meth/eth/prop/but anoic acid)

Question 29

Salts of carboxylic acid

Answer 29

These are weak acids They react with bases, metals and carbonates Methanoate HCOO- Ethanoate CH3COO- Propanoate C2H5COO- Butanoate C3H7COO-

Question 30

Reactions of carboxylic acids with carbonates

Answer 30

Equation: Carbonate + acid —> salt + water + carbon dioxide Test: As releases carbon dioxide turns colourless limewater to milky

Question 31

Reactions of carboxylic acids with metals

Answer 31

Equation: Metal + acid —> salt + hydrogen Test: gives a pop when tested with a lighted splint

Question 32

Reactions of carboxylic acids with bases

Answer 32

Equation: Base + acid —> salt + water

Question 33

Crude oil (petroleum)

Answer 33

A mixture containing mainly alkane hydrocarbons

Question 34

Petrochemicals

Answer 34

Chemicals made from petroleum and natural gas

Question 35

Finite resource

Answer 35

A resource that once used, cannot be replaced in a human lifetime

Question 36

Is searlait a bitch

Answer 36

Yes

Question 37

Fraction

Answer 37

A mixture of molecules with similar boiling points

Question 38

4 steps in fractional distillation

Answer 38

- crude oil is heated and vaporised - the vaporised crude oil enters a fractionating tower which is hotter at the bottom and cooler at the top - the hydrocarbons cool as they rise up the tower and condense at different heights because they have different boiling points - hydrocarbons with large molecules are collected near the bottom of the tower while those with small molecules are collectedd at the top

Question 39

All different fractions and there uses

Answer 39

- Refinery gas for bottled gases - Petrol used as a fuel for cars - Naptha for manufacture of chemicals and plastics - Kerosene as a fuel for aircraft - Diesel as a fuel for cars and trains - Fuel oils used for fuels for ships - Bitumen used to surface roads and roofs

Question 40

Cracking

Answer 40

The breakdown of larger saturated hydrocarbons (alkanes) into smaller more useful ones, some of which are unsaturated (alkenes) Carried out be heating, it is a thermal decomposition reaction because alkanes are broken down into smaller molecules using heat