Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
Practical: making and testing the smell of some esters in the lab
19 practice questions
Practice questions
11–19 of 19
Question 11
4 marks · Normal
Answer and see the solution →The table shows results from making esters by reacting different combinations of carboxylic acids and alcohols using the laboratory method described.
Combinations of acids and alcohols used to make esters Carboxylic acid Alcohol Ester layer observed? Odour Ethanoic acid Ethanol Yes Sweet, fruity Ethanoic acid Propan-1-ol Yes Pear drop Butanoic acid Ethanol Yes Sweet, fruity Propanoic acid Propan-1-ol No - (a)[1 mark]Suggest a reason why no ester layer was observed in the last experiment, compared to the others.
(b)[1 mark]State one observation that would indicate an ester had formed in the other experiments.
(c)[2 marks]In the experiment where ethanoic acid and propan-1-ol were used, what extra precaution should be taken when smelling the product? Explain your answer.
Question 12
1 mark · Normal
Answer and check →Which one of these is an essential safety step when preparing esters in the laboratory?
- A.Smell the product directly from the top of the beaker
- B.Wear safety goggles throughout the experiment
- C.Heat the mixture using a strong Bunsen flame
- D.Add all the reactants together before mixing
Question 13
2 marks · Normal
Answer and see the solution →State two reasons why sodium carbonate solution is added at the end of the ester preparation process.
Question 14
4 marks · Normal
Answer and see the solution →A chemistry student mixes methanol and butanoic acid to make an ester using the laboratory method.
(a)[1 mark]Name the ester formed.
(b)[2 marks]Briefly outline the apparatus set-up used for heating the reaction mixture safely.
(c)[1 mark]How would you test for the presence of the ester after the reaction is complete?
Question 15
3 marks · Normal
Answer and see the solution →A student prepares an ester in the lab by reacting 1.0 cm³ of propanoic acid (density = 1.01 g/cm³, molar mass = 74 g/mol) with an excess of methanol in the presence of a few drops of concentrated sulfuric acid. After the reaction, they transfer the contents to water to isolate the ester layer.
Calculate the maximum mass of methyl propanoate that could be formed from the propanoic acid used.
Question 16
3 marks · Normal
Answer and see the solution →Describe how esters can be made and separated in the laboratory. In your answer, explain the roles of each of the following:
(a) concentrated sulfuric acid,
(b) the hot water bath,
(c) adding sodium carbonate solution after the reaction.
Question 17
2 marks · Hard
Answer and see the solution →State the role of sulfuric acid in the laboratory preparation of an ester. Explain why only a few drops are added.
Question 18
5 marks · Hard
Answer and see the solution →A student is asked to prepare a sample of butyl propanoate, an ester, using only laboratory equipment and chemicals available at school.
(a)[1 mark]Write the names of the alcohol and the carboxylic acid required to make butyl propanoate.
(b)[3 marks]Describe, in order, the main steps the student should follow to prepare and purify butyl propanoate in the laboratory.
(c)[1 mark]State how the student can safely test for the smell of the product once separated.
Question 19
2 marks · Hard
Answer and see the solution →During the purification step in ester preparation, the mixture is poured into sodium carbonate solution. Explain the purpose of this step and describe what you would observe.