C10 - Organic reactions

Question 1

What is a functional group?

Answer 1

the part of a molecule that determines its characteristic reactions, regardless of the composition of the rest of the molecule

eg the C=C bond in alkenes

Question 2

How do alkenes burn?

Answer 2

they combust in the same way as other organic molecules, but produce a smokier flame due to incomplete combustion

Question 3

Name the first 4 alkenes:

Answer 3

ethene, propene, butene, pentene

Question 4

What is an addition reaction?

Answer 4

a reaction where an atom/molecule reacts with another unsaturated molecule, and is “added” onto it via a covalent bond, forming a new singular molecule

Question 5

What addition reactions can alkenes do, and what are their products?

Answer 5

-hydrogen (alkanes)

-water (alcohols)

-halogens (di-halogenoalkane)

Question 6

What are alcohols? Give 2 of their properties:

Answer 6

-a homologous series with the -OH functional group

-flammable
-soluble (dissolves to form neutral solution)

alcOHol

Question 7

How does an alcohol react when sodium is added?

Answer 7

produces sodium-(alkyl prefix)-oxide + hydrogen
(eg ethoxide)

very alkaline solution

Similar to the reaction of water with sodium, but less vigorous

Question 8

What are the products when an alcohol undergoes combustion?

Answer 8

forms CO₂+H₂O

Note that this is different to being oxidised

Question 9

What happens when an alcohol reacts with oxygen through an oxidising agent?

Answer 9

forms a carboxylic acid and water

Note that this is different to combustion

Question 10

Using a displayed formula, show how an alcohol is oxidised by an oxidising agent:

Answer 10

Question 11

What is the test for alcohols?

Answer 11

-add acidified potassium dichromate (oxidising agent)
-if alcohol present, goes from orange to green

Question 12

How are the processes of combustion and oxidation different in terms of reacting alcohols?

Answer 12

-combustion is a way to oxidise an alcohol
-oxidation is another way that involves a chemical oxidising agent (like potassium dichromate (VI))

Question 13

What are some uses of alcohols? Give some extra uses for specifically ethanol too:

Answer 13

-fuels (flammable)
-solvents in industry (better solvents than water)

ethanol
-hand sanitisers
-alcoholic drinks

Alcohols can dissolve hydrocarbons and lipids, but water can’t

Question 14

How can you produce ethanol?

Answer 14

-fermentation

-ferment sugar solutions using yeast to form an aqueous solution of ethanol

Question 15

What conditions are needed to produce ethanol by fermentation?

Answer 15

-37°C
-water
-presence of yeast
-no oxygen

Fermentation is just anaerobic respiration that occurs in yeast, so it must be placed in anaerobic conditions

Question 16

What are carboxylic acids?

Answer 16

homologous series with -COOH functional group, that partially ionises in aqueous solution (weak acid)

-COOH is known as a carboxyl group, because it’s formed from a carbonyl C=O group and a hydroxyl -OH group

Question 17

How does a carboxylic acid react with a carbonate?

Answer 17

produces alkyl…oate salt, CO₂, and H₂O

same as when any acid reacts with a carbonate

Question 18

Give the formula for methanoic acid:

Answer 18

HCOOH

the smallest carboxylic acid

Question 19

How do carboxylic acids react with alcohols?

Answer 19

forms ester + water

An acid, usually sulfuric acid, is used to catalyse this reversible reaction

Question 20

What are esters?

Answer 20

homologous series with the -COO- functional group

Identified by their fruity smell, and they are also very volatile

Question 21

Give an example of an ester, and how it can be made:

Answer 21

react ethanoic acid with ethanol to form ethyl ethanoate (CH₃COOC₂H₅)

produces water too

Question 22

Draw a displayed formula equation to show the reaction between ethanoic acid and ethanol

Answer 22