Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Acids, Alkalis and Titrations
83 practice questions
Topics covered
Practice questions
21–30 of 35 · Easy
Question 21
3 marks · Easy
Answer and see the solution →Read the passage and answer the questions below. Acids release hydrogen ions ([32mH^+[0m) in water, making the solution acidic.
(a)[1 mark]Name the ion formed in solution when hydrochloric acid is added to water.
(b)[1 mark]Give the symbol for this ion.
(c)[1 mark]Explain, using the equation, what happens when [32mHCl[0m is dissolved in water.
Question 22
3 marks · Easy
Answer and see the solution →The following table shows the formulae of several acids. Use the table to answer the questions below.
Table 1. Some common acids and their formulae. Acid Formula Hydrochloric acid HCl Nitric acid HNO₃ Sulfuric acid H₂SO₄ Phosphoric acid H₃PO₄ Ethanoic acid CH₃COOH (a)[1 mark]Identify the ion that all acids in the table produce when dissolved in water.
(b)[1 mark]State the chemical symbol and charge of this ion.
(c)[1 mark]Explain, using the formulae in the table, how you know that each acid can form this ion.
Question 23
2 marks · Easy
Answer and see the solution →A student dissolves 0.20 mol of sodium carbonate (Na_2CO_3) in enough water to make 1.0 dm³ of solution. Sodium carbonate forms an alkaline solution because it reacts to produce hydroxide ions.
Calculate the concentration of carbonate ions (CO_3^{2-}) present in the solution. Give your answer in mol/dm³.
Question 24
1 mark · Easy
Answer and see the solution →Name the piece of apparatus used to deliver small, measured volumes of acid into a conical flask during a titration.
Question 25
3 marks · Easy
Answer and see the solution →(a)[1 mark]State the colour change you would see when phenolphthalein is used as the indicator and the alkali in the conical flask is just neutralised by the acid from the burette.
(b)[1 mark]Give one reason why phenolphthalein is preferred over universal indicator for titrations.
(c)[1 mark]Name the flask used to hold the solution during a titration.
Question 26
2 marks · Easy
Answer and see the solution →During a titration, a student records an initial burette reading of 6.40 cm³ and a final reading of 28.15 cm³. Calculate the volume of solution delivered from the burette.
Question 27
2 marks · Easy
Answer and see the solution →Explain why titration readings should be recorded to two decimal places.
Question 28
3 marks · Easy
Answer and see the solution →(a)[1 mark]Titration Results Titration Initial burette reading / cm³ Final burette reading / cm³ 1 0.70 18.35 2 1.40 19.80 3 2.00 20.45 Calculate the titre (volume delivered) for Titration 1.
(b)[1 mark]Which titration is likely to be the rough (trial) titration? Give a reason for your answer.
(c)[1 mark]Suggest why the average titre is calculated using only concordant results.
Question 29
1 mark · Easy
Answer and see the solution →State the name of the procedure used to determine the volume of acid needed to neutralise a fixed volume of alkali.
Question 30
3 marks · Easy
Answer and see the solution →(a)[1 mark]Describe how you would add the alkali during a titration to obtain an accurate result.
(b)[1 mark]Explain why the conical flask should be swirled during the titration.
(c)[1 mark]State how the endpoint of the titration is recognised.