Section 6 - Organic Chemistry P2 Flashcards
What are the different types of homologous series?
alkanes alkenes alcohols carboxylic acids esters
What is the functional group of alcohols?
an oxygen hydrogen bond
What is the functional group of carboxylic acids?
a carbon oxygen double bond and carbon hydroxide bond
What is the functional group of esters?
a carbon oxygen double bond and a carbon oxygen bond
What is the prefix/suffix of alcohols?
-ol
What is the prefix/suffix of carboxylic acids?
-oic acid
What is the prefix/suffix of esters?
Prefix: alkyl- -yl
Suffix: -anoate
How could isomers be arranged differently?
The same atoms could be arranged into different functional groups
What are the properties of isomers which have different functional groups?
Physical and chemical properties are both very different
What is the general formula for alcohols?
CₙH₂ₙ₊₁OH
What functional group do all alcohols contain?
-OH functional group
What are the first four alcohols in the homologous series?
methanol
ethanol
propanol
butanol
What different ways can the functional group be shown for an alcohol?
- the -OH group can be attached to different carbon atoms in the chain
- alcohols can have more than one -OH group
What happens when something is oxidised?
It gains oxygen
When alcohols are oxidised what happens?
- alcohols oxidise to form carboxylic acids
- for this you need an oxidising agent (such as potassium dichromate(VI) in dilute sulphuric acid
What happens when ethanol is heated with acidified potassium dichromate(VI)?
Ethanoic acid is produced (CH₃COOH)
What is microbial oxidation?
- some microorganisms are able to use alcohols as an energy source
- to do this they use oxygen in the air to oxidise alcohols, carboxylic acids are formed as a by-product
When alcohols are burnt what occurs?
- when alcohols are burnt in enough oxygen they undergo complete combustion
- the products of this reaction are water and carbon dioxide
How is ethene produced?
By cracking crude oil
What will ethene and steam react together to produce?
And what type of reaction is it?
ethanol
an addition reaction
How can ethanol be made?
- by reacting ethene and steam
- by fermenting glucose with yeast
What conditions are needed for ethene to react with steam?
- temperature of 300°C
- pressure of 60-70 atmospheres
- phosphoric acid is used as a catalyst
What is the trouble with producing ethanol from ethene and steam?
-at the moment it is a cheap process (ethene is fairly cheap and not much is wasted) BUT crude oil is a non-renewable resource which will start running out so it will become expensive to make ethanol from this
What is alcohol in beer and wine made from?
Fermentation of glucose which is converted into ethanol and carbon dioxide by yeast
What does yeast do in fermentation?
-yeast cells contain an enzyme (enzymes are naturally occurring catalysts)
What are the conditions required for fermentation?
- mixture at about 30°C (optimum temperature for the enzymes, too hot would denature the enzymes)
- anaerobic conditions(no oxygen) - oxygen turns ethanol into ethanoic acid(vinegar)
What are the advantages of making ethanol from fermentation?
-all the raw materials are all renewable sources
(sugar from sugar cane is grown as a major crop in several parts of the world)
(yeast is easy to grow)
What are the disadvantages of making ethanol from fermentation?
- the ethanol you get from this process isn’t very concentrated, so it needs to be distilled to increase its strength
- it also needs to be purified
What is the functional group of the carboxylic acid homologous series?
-COOH
has a C=O double bond and a C-OH bond, all coming off the same C
What are the first four names of the carboxylic acids?
methanoic acid (HCOOH) ethanoic acid (CH₃COOH) propanoic acid (CH₃CH₂COOH) butanoic acid (CH₃CH₂CH₂COOH)
If a carboxylic acid reacts to form a salt, what do the name of the salt end in?
- anoate
e. g. ethanoate
What do carboxylic acids in an aqueous solution react with metal carbonates to form?
salt + water + carbon dioxide
What do aqueous carboxylic acids react with metals to form?
salt + hydrogen
How are carboxylic acids used in the preparations of esters?
-carboxylic acids react with alcohols in the presence of an acid catalyst to form esters
What is vinegar?
ethanoic acid dissolved in water
-vinegar is used for flavouring and preserving food
alcohol + carboxylic acid –>
ester + water
an acid catalyst is usually used
What functional group do esters have?
-COO-
What do ester names end in?
-oate
How do you name esters?
The alcohol forms the first part of the esters name, and the acid forms the second part of the esters name
Describe a practical to make ethyl ethanoate:
- add 4 drops of concentrated sulphuric acid to a boiling tube using a dropping pipette
- add 10 drops of ethanoic acid
- add an equal volume of ethanol
- place the boiling tube in a beaker on a tripod
- heat using a bunsen burner until the water starts to boil then turn the bunsen burner off
- after 1 minute, remove the tube and allow it to cool
- pour the mixture into a test tube of sodium carbonate solution and mix, a layer of eater should form on the top (should smell sweet, like pear drops)
What are the features of esters?
- many esters have pleasant smells
- volatile (they evaporate into gases very quickly)
What are the uses of esters?
- used in perfumes
- used to make food flavourings
What does condensation polymerisation involve?
Usually involves two different types of monomers
How can polymers be made?
by condensation polymerisation
What is the process of polymers being made from condensation polymerisation?
- the monomers react together and bonds form between them, making polymer chains
- each monomer has to contain at least two functional groups, one on each end of the molecule
- each functional group react with the functional group of another monomer, creating long chains of alternating monomers (each new bond that forms, a small molecule is lost)
When do polyesters form?
Polyesters form when dicarboxylic acid monomers and diol monomers react together
What two carboxylic acid groups are in the dicarboxlic acid monomers and diol monomers?
two alcohol (-OH) groups
What is an ester link?
When the carboxylic acid group reacts with the alcohol group
What are polyesters?
Polyesters are condensation monomers - each time an ester link is formed, a molecule of water is lost
What are biopolyesters?
Biodegradable polyesters
-can be broken down by bacteria and other living organisms in the environment over time (they decompose and and don’t stay in landfill forever reducing the polymers’ pollutant effect
What are examples of biopolyesters?
Some polyesters
