Esters (Edexcel IGCSE Chemistry (Modular): Unit 2): Flashcards
Exam code: 4XCH1
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- FrontWhat are Esters?
Define esterification.
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Cards in this collection (15)
Define esterification.
Esterification is the reaction between an alcohol and a carboxylic acid to produce an ester and water.
What is the functional group of an ester?
The functional group of an ester is -COO-, which connects two carbon chains in the general structure R-COO-R.
True or False?
Esters are formed from two carboxylic acids reacting together.
False.
Esters are formed from a carboxylic acid and an alcohol reacting together, not two carboxylic acids.
What is ethyl ethanoate?
Ethyl ethanoate is an ester formed when ethanoic acid reacts with ethanol in the presence of concentrated sulfuric acid as a catalyst.
In an ester's name, the first part comes from the .......... and ends in '-yl', while the second part comes from the .......... and ends in '-oate'.
In an ester's name, the first part comes from the alcohol and ends in '-yl', while the second part comes from the carboxylic acid and ends in '-oate'.
Why is concentrated sulfuric acid used in esterification?
Concentrated sulfuric acid acts as a catalyst in esterification, speeding up the reaction between the alcohol and carboxylic acid without being used up.
True or False?
Esters are used as food flavourings and perfumes.
True.
Esters are sweet-smelling oily liquids, which makes them useful as food flavourings and in perfumes.
What are the products when ethanoic acid reacts with ethanol?
When ethanoic acid reacts with ethanol, the products are ethyl ethanoate (an ester) and water.
The equation is: CH3COOH + C2H5OH → CH3COOC2H5 + H2O
Complete the table to show the name of each ester.
Alcohol
Carboxylic acid
Ester name
ethanol
ethanoic acid
pentanol
butanoic acid
methanol
propanoic acid
Complete the table to show the name of each ester.
Alcohol
Carboxylic acid
Ester name
ethanol
ethanoic acid
ethyl ethanoate
pentanol
butanoic acid
pentyl butanoate
methanol
propanoic acid
methyl propanoate
What three reagents are mixed to prepare ethyl ethanoate in the laboratory?
The three reagents are:
Ethanoic acid
Ethanol
Concentrated sulfuric acid (as catalyst)
True or False?
A Bunsen burner can be used to heat the esterification mixture.
False.
Ethanol is flammable, so a Bunsen burner cannot be used. The mixture is heated using a water bath or an electric heater instead.
Why is the ester distilled off as soon as it forms during the preparation of ethyl ethanoate?
The ester is distilled off immediately because esters have low boiling points and are volatile. Removing the ester as it forms prevents the reverse reaction from occurring, increasing yield.
To remove acidic impurities from the distillate, .......... solution is added until the mixture stops fizzing. To remove ethanol, .......... solution is added.
To remove acidic impurities from the distillate, sodium carbonate solution is added until the mixture stops fizzing. To remove ethanol, calcium chloride solution is added.
How can you confirm that an ester has been produced in the preparation of ethyl ethanoate?
You can confirm an ester has been produced by smelling the distillate — esters have a characteristic sweet smell.
Define distillation in the context of ester preparation.
Distillation is a separation technique in which a mixture is heated so that the most volatile component evaporates first and is then condensed and collected separately.
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