ORGANIC REACTIONS

Question 1

What does unsaturated mean?

Answer 1

Two fewer hydrogen atoms than an alkane with the same number of carbon atoms. Has a double carbon bond.

Question 2

What is a functional group?

Answer 2

Part of the molecule that determines how it reacts eg a double bond in an alkene.

Question 3

What is a homologous series?

Answer 3

Members of this series all have the same functional group.

Question 4

How do alkenes burn?

Answer 4

With a smoky, yellower flame due to incomplete combustion. They also release less energy than alkanes, for this reason.

Question 5

What is hydrogenation?

Answer 5

When alkenes react with hydrogen. A Nickle catalyst and 150 degrees Celsius is necessary.
Hydrogen is added across the double bond so the double bind is converted to a single bond. This produces an alkane.

Question 6

What is hydration?

Answer 6

Reaction of an alkene with water. 
Makes an alcohol. 
300 degrees Celsius 
Must be steam 
70 atmospheres pressure 
Phosphoric avid catalyst 
Reversible.

Question 7

How can ethanol be made?

Answer 7

The hydration of ethene.
High yield
Non renewable source
High temp/energy

OR
Fermentation 
Anaerobic conditions 
Low temp/energy
Renewable 
Makes an aqueous solution (ethanol dissolved in water) so need s to be purified through distillation which requires energy.

Question 8

What are the products of methanol and sodium?

Answer 8

Sodium methoxide and hydrogen

Question 9

What are the products of methanol and an oxidising agent?

Answer 9

Methanoic acid and water.

Question 10

What are the products of ethanoic acid and sodium carbonate?

Answer 10

Sodium ethanoate and carbon dioxide and water.

Question 11

What are the products of ethanoic acid and ethanol?

Answer 11

Ethyl ethanoate.

Requires sulphuric acid as a catalyst

Question 12

What are the products of methanoic acid and magnesium?

Answer 12

Magnesium methanoate and hydrogen.

Question 13

What are the products of propanoic acid and lead carbonate?

Answer 13

Lead propanoate and carbon dioxide.

Question 14

What are the products of ethanoic acid and copper oxide?

Answer 14

Cooper ethanoate and water.

Question 15

Why are alkenes more reactive than alkanes?

Answer 15

Because of their double bond. Molecules that react with alkene molecules ‘add’ to the alkene across their double bond.

Question 16

How do you test for ethene?

Answer 16

Using bromine water. Ethene takes the orange colour out of the reaction mixture and leaves it colourless.

Question 17

What happens when an alkene reacts with hydrogen?

Answer 17

The double bond in alkenes mean that they are unsaturated compounds, so their molecules do not contain the maximum number of hydrogen atoms possible.
By the addition of a hydrogen molecule across the double bond a saturated hydrocarbon, AN ALKANE, will be formed.

Question 18

What conditions are needed for an alkene to react with hydrogen to form an alkane?

Answer 18

60 degrees celcius and the presence of a nickle catalyst.

Question 19

Why are alkenes reacted with hydrogen?

Answer 19

To straighten their molecules and increase their melting points. For example, the right amount of hydrogen is added to make a margarine that will spread easily straight from the fridge.

Question 20

What happens when alkenes react with water?

Answer 20

Ethanol can be made from ethene gas. Ethene gas can react with steam to make ethanol.

Question 21

What conditions are needed for alkenes to react with water?

Answer 21

The reaction requires energy to heat the gases and to generate a high pressure.

The reaction is reversible, so ethanol can break down back into ethene and steam. So, unreacted ethene and steam are recycled over the catalyst.

Question 22

How is the organic structure of an alcohol molecule written?

Answer 22

Replace one of the -H from an alkane molecule and change it to an -OH.

Question 23

What are the first four alcohols in the homogolous series?

Answer 23

Methanol
Ethanol
Propanol
Butanol

Question 24

What is the functional group of carboxylic acids?

Answer 24

-COOH

Question 25

What are the first four carboxylic acids in the homogolous series?

Answer 25

Methanoic acid Ethanoic acid Propanoic acid Butanoic acid

Question 26

Esters?

Answer 26

???

Question 27

How is ethanol made?

Answer 27

Made by fermenting sugars from plant material with yeast and is becoming an important alternative fuel to petrol and diesel. Ethanol made by fermentation is termed a biofuel. Can also be made in the industry from reacting ethene and steam in the presence of a catalyst. However, this method uses up some of the diminishing supplies of crude oil, a non-renewable resource.

Question 28

What are some uses of alcohols?

Answer 28

Solvents in products such as perfumes, aftershaves and mouthwashes.

Question 29

What happens during the combustion of alcohols?

Answer 29

Very flammable. It burns with a 'clean' blue flame.

Question 30

What happens when alcohols react with sodium?

Answer 30

The sodium effervesces (gives off bubbles of gas), producing hydrogen gas, and gets smaller and smaller as it forms a solution of sodium ethoxide in the ethanol. The reaction isn't a vigorous as the reaction observed between water and sodium.

Question 31

What happens during the oxidation of alcohols?

Answer 31

Combustion is one way to oxidise an alcohol. However, when you use chemical oxidising agents such as potassium dichromate, you get different products. An alcohol is oxidised to a carboxylic acid when boiled with acidified potassium dichromatebsolution. Ethanol can be oxidised to ethanoic acid if it is left oxposed to air. Microbes in the air produce ethanoic acid from ethanol.

Question 32

What is ethanoic acid?

Answer 32

Vinegar.

Question 33

What are some typical reactions of carboxylic acids?

Answer 33

Reaction with a metal carbonate forms a salt, water and carbon dioxide.

Question 34

What practical can be done to test the properties of an ethanoic acid solution?

Answer 34

Take the pH of the solution Add a little potassium carbonate to the acid Add a small piece of magnesium ribbon to the acid. Test the conductivity of the solution in a small beaker using a simple circuit of a cell, two carbon electrodes, and a bulb. Collect the gas given off the negative electrode in a test tube. Then test it with a lighted spill.

Question 35

Why are carboxylic acids called weak acids?

Answer 35

Carbon dioxide gas is given off more slowly when a metal carbonate reacts with a carboxylic acid, as compared with hydrochloric acid of the same concentration. That is because carboxylic acids are weak acids as opposed to strong acids, such as sulfuric acid or hydrochloric acid. Acids must dissolve in water before they show their acidic properties. That is because in water all acids ionise (split p).