Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Organic Chemistry
785 practice questions
Topics covered
Practice questions
571–580 of 785
Question 571
2 marks · Easy
Answer and see the solution →A student reacts 1.2 g of magnesium with excess propanoic acid.
Calculate the maximum volume of hydrogen gas produced at room temperature and pressure. (Molar mass of Mg = 24 g/mol, 1 mol gas = 24 dm³ at r.t.p.)
Question 572
2 marks · Normal
Answer and see the solution →State the products formed when magnesium metal reacts with dilute propanoic acid. Write a balanced chemical equation for this reaction.
Question 573
4 marks · Normal
Answer and see the solution →Ethanoic acid is a commonly used carboxylic acid.
(a)[1 mark]State the term used to describe the strength of ethanoic acid as an acid.
(b)[1 mark]Describe how ethanoic acid affects blue litmus paper.
(c)[1 mark]Suggest a typical pH value for a solution of ethanoic acid.
(d)[1 mark]Compare the reaction rate of magnesium with ethanoic acid to the reaction rate with hydrochloric acid. State which is faster and explain why.
Question 574
3 marks · Normal
Answer and see the solution →Carboxylic acids are classified as weak acids.
(a)[1 mark]Explain what is meant by a 'weak acid'.
(b)[1 mark]Describe what you would observe when sodium carbonate solution is added to ethanoic acid.
(c)[1 mark]State how the reaction of ethanoic acid with sodium carbonate shows its weak acid properties.
Question 575
4 marks · Normal
Answer and see the solution →The table below shows the reaction of four different carboxylic acids with magnesium ribbon. In each case, 10 cm³ of acid at the same concentration is used. The time taken for the reaction to stop is measured:
Carboxylic Acid Time taken for reaction to stop / s methanoic acid 110 ethanoic acid 98 propanoic acid 99 butanoic acid 112 (a)[1 mark]Which acid reacts fastest with magnesium ribbon? Support your answer using data.
(b)[1 mark]Suggest why the reactions do not all take the same time, even though the acids are at the same concentration.
(c)[1 mark]Write the formula for the salt formed when butanoic acid reacts with magnesium.
(d)[1 mark]State one safety precaution when carrying out these reactions.
Question 576
1 mark · Normal
Answer and check →Which statement best describes a weak acid such as ethanoic acid?
- A.It ionises completely in water.
- B.It ionises partially in water.
- C.It does not ionise in water.
- D.It is less dense than water.
Question 577
2 marks · Normal
Answer and see the solution →Give the name and the molecular formula of the carboxylic acid with three carbon atoms.
Question 578
4 marks · Normal
Answer and see the solution →A student adds blue litmus paper to a solution of butanoic acid then tests its pH before and after adding sodium carbonate. Answer the following questions.
(a)[1 mark]State what is observed when the blue litmus paper is placed in butanoic acid.
(b)[1 mark]Give a likely pH value for butanoic acid.
(c)[1 mark]State what you would observe after adding sodium carbonate to the butanoic acid.
(d)[1 mark]Explain why the pH of the solution increases after adding sodium carbonate.
Question 579
3 marks · Normal
Answer and see the solution →A student reacts 4.8 g of magnesium ribbon with excess ethanoic acid. Magnesium reacts with ethanoic acid as shown:
Calculate the maximum volume of hydrogen gas produced at room temperature and pressure (rtp), assuming 1 mole of gas occupies 24 dm³. (Relative atomic mass: Mg = 24)
Question 580
2 marks · Hard
Answer and see the solution →Butanoic acid and hydrochloric acid have the same concentration. Explain why the pH of butanoic acid is higher than that of hydrochloric acid.