Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Organic Chemistry
785 practice questions
Topics covered
Practice questions
271–280 of 335 · Normal
Question 271
4 marks · Normal
Answer and see the solution →(a)[1 mark]Give the names of the starting alcohol and carboxylic acid used to prepare propyl ethanoate in the laboratory.
(b)[2 marks]Briefly describe the steps you would take to make a small sample of propyl ethanoate, including any safety precautions.
(c)[1 mark]State how you would detect the formation of propyl ethanoate after the reaction.
Question 272
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 273
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 274
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 275
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 276
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 277
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 278
6 marks · Normal
Answer and see the solution →Butanol and ethanoic acid are used together in a laboratory to produce an ester. Answer the following questions about this reaction and the practical steps involved.
(a)[1 mark]Name the ester formed in this reaction.
(b)[2 marks]Draw the structural formula for the ester you named in part (a).
(c)[1 mark]State the name of the catalyst used during this esterification reaction.
(d)[2 marks]Describe one step you would take in the laboratory to make the smell of the ester easier to detect after the reaction is complete.
Question 279
6 marks · Normal
Answer and see the solution →A student wants to prepare methyl propanoate in the laboratory using appropriate organic starting materials.
(a)[2 marks]Identify the alcohol and the carboxylic acid required to make methyl propanoate.
(b)[2 marks]Draw the structural formula for methyl propanoate.
(c)[2 marks]Describe briefly, in two steps, how a small sample of methyl propanoate can be prepared and the smell detected during a school practical.
Question 280
6 marks · Normal
Answer and see the solution →A group of students carried out an experiment to produce an ester from ethanol and propanoic acid. They left the product to stand after completing the practical.
(a)[2 marks]Explain how the students could confirm that an ester had formed, even if the reactants and product are colourless.
(b)[1 mark]Ethyl propanoate is an ester. Give the name of the alcohol used to manufacture this ester.
(c)[1 mark]The mixture was poured into a beaker containing sodium carbonate solution. Suggest a reason for this step.
(d)[2 marks]Explain why small esters are easy to separate from the reaction mixture compared to the carboxylic acid and alcohol used.