Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Organic Chemistry
785 practice questions
Topics covered
Practice questions
461–470 of 785
Question 461
3 marks · Easy
Answer and see the solution →(a)[1 mark]Describe the observable change in colour that occurs when ethanol is oxidised by heating with potassium dichromate(VI) in dilute sulfuric acid.
(b)[1 mark]What does this colour change indicate about the potassium dichromate(VI) during the reaction?
(c)[1 mark]Suggest what you would observe if the solution is heated without adding ethanol.
Question 462
2 marks · Easy
Answer and see the solution →Ethanol can be oxidised by heating it with potassium dichromate(VI) in dilute sulfuric acid.
Calculate the number of different substances (including ethanol and all reagents used) that must be present in the test-tube for this reaction to occur, according to standard laboratory practice.
Show your working.
Question 463
2 marks · Easy
Answer and see the solution →The oxidation of ethanol with potassium dichromate(VI) requires dilute sulfuric acid.
A chemist accidentally forgets to add any dilute sulfuric acid to the test-tube, while potassium dichromate(VI) and ethanol are both present.
Calculate the number of moles of H+ ions available to the reaction in this mistake, assuming none are present in the other reagents.
Show your working and state the reason for your answer.
Question 464
2 marks · Normal
Answer and see the solution →Describe what happens when ethanol is oxidised by heating it with potassium dichromate(VI) in dilute sulfuric acid.
Question 465
3 marks · Normal
Answer and see the solution →Explain, using your knowledge of acids and oxidation reactions, why dilute sulfuric acid is needed for potassium dichromate(VI) to oxidise ethanol.
Question 466
3 marks · Normal
Answer and see the solution →Ethanol is sometimes used to make vinegar by oxidation. Explain, in terms of the laboratory process, how a chemist could use potassium dichromate(VI) and dilute sulfuric acid to produce ethanoic acid from ethanol.
Question 467
4 marks · Normal
Answer and see the solution →The table shows the initial and final colours observed when ethanol is heated with potassium dichromate(VI) and dilute sulfuric acid.
Observation of Colour Changes during Oxidation Test Initial colour Final colour A Orange Green B Orange Orange C Orange Green Explain what has happened in each test. Suggest a reason why the outcome was different in test B.
Question 468
1 mark · Normal
Answer and check →Which statement best explains the role of dilute sulfuric acid in the oxidation of ethanol with potassium dichromate(VI)?
- A.It provides hydrogen ions needed for the reaction.
- B.It acts as a catalyst for ethanol oxidation.
- C.It reacts with ethanol to make ethene.
- D.It neutralises the potassium dichromate(VI).
Question 469
2 marks · Normal
Answer and see the solution →State the reagents and conditions required to oxidise ethanol to ethanoic acid in the laboratory.
Question 470
4 marks · Normal
Answer and see the solution →(a)[1 mark]What is the appearance of the potassium dichromate(VI) solution before ethanol is added?
(b)[2 marks]Describe the appearance of the solution after heating with ethanol.
(c)[1 mark]What does the observed colour change indicate about the reaction?