Chemistry
Acids, bases and salts — Topic 8
- 1.
25.0 cm³ of 0.100 mol/dm³ sulfuric acid neutralises sodium hydroxide. Calculate the moles of sulfuric acid and the moles of sodium hydroxide required. Use H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O.
[4 marks] - 2.
Describe how to prepare pure, dry copper(II) sulfate crystals from dilute sulfuric acid and excess copper(II) oxide.
[5 marks] · no calculator - 3.
State the colour changes of litmus, methyl orange and phenolphthalein indicators when moving from acidic to alkaline solutions.
[3 marks] · no calculator - 4.
Define a strong acid and a weak acid in terms of dissociation, and state whether hydrochloric acid and ethanoic acid are strong or weak.
[4 marks] · no calculator - 5.
Describe how you would prepare a pure, dry sample of soluble sodium chloride crystals by titration, starting from dilute hydrochloric acid and dilute sodium hydroxide.
[5 marks] · no calculator - 6.
Write the ionic equation for the neutralisation reaction between any strong acid and any strong alkali in aqueous solution.
[2 marks] · no calculator - 7.
Explain why a solution with pH 3 is ten times more acidic than a solution with pH 4, in terms of hydrogen ion concentration.
[3 marks] · no calculator - 8.
Describe a test to confirm the presence of carbonate ions in a solid sample, and state the expected observation.
[3 marks] · no calculator - 9.
Distinguish between a soluble salt and an insoluble salt, and outline the different method used to prepare each from its constituent ions.
[4 marks] · no calculator - 10.
State the general word equation for the reaction between a metal and an acid, and identify the gas produced.
[3 marks] · no calculator - 11.
Classify each of the following oxides as acidic, basic or amphoteric: sulfur dioxide (SO₂), calcium oxide (CaO), and aluminium oxide (Al₂O₃). State one property that identifies an amphoteric oxide.
[4 marks] · no calculator - 12.
Describe a test to confirm the presence of ammonia gas, and state the observation.
[2 marks] · no calculator - 13.
Black copper(II) oxide is added in excess to warm dilute sulfuric acid: CuO + H₂SO₄ → CuSO₄ + H₂O. State what would be observed as the oxide is added, and explain how you would know when the reaction is complete.
[3 marks] · no calculator - 14.
Describe a test to confirm the presence of sulfate ions in solution, including the reagents used and the expected observation.
[3 marks] · no calculator - 15.
Describe a test to confirm the presence of chloride ions in solution, including the reagents used and the expected observation.
[3 marks] · no calculator - 16.
Describe how a pure sample of insoluble lead(II) sulfate could be prepared from solutions of lead(II) nitrate and sodium sulfate, and write the ionic equation, including state symbols, for the reaction.
[5 marks] · no calculator - 17.
State one advantage of using a universal indicator or a pH meter over a single indicator such as litmus, when investigating the acidity or alkalinity of a solution.
[2 marks] · no calculator - 18.
State what is meant by the basicity of an acid, and state the basicity of hydrochloric acid and of sulfuric acid.
[3 marks] · no calculator - 19.
Describe a test to confirm the presence of ammonium ions in a solid sample.
[3 marks] · no calculator - 20.
A student mixes dilute hydrochloric acid with dilute sodium hydroxide solution in an insulated cup and measures a rise in temperature. State the type of reaction this shows neutralisation to be, and state what would happen to the temperature rise if the experiment were repeated using half the volume of each solution (at the same concentrations).
[3 marks] · no calculator - 21.
Calcium carbonate reacts with dilute hydrochloric acid: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂. State whether the calcium chloride salt formed is soluble or insoluble, and state two observations you would expect to see during this reaction.
[3 marks] · no calculator - 22.
State the difference between the terms 'anhydrous' and 'hydrated' as applied to salts, giving an example of each for copper(II) sulfate.
[3 marks] · no calculator - 23.
Silver nitrate solution is mixed with sodium chloride solution, forming a precipitate. Write the full ionic equation, including state symbols, for this reaction, and name the precipitate formed.
[3 marks] · no calculator - 24.
Calculate the volume of 0.20 mol/dm³ hydrochloric acid required to react exactly with 20.0 cm³ of 0.15 mol/dm³ calcium hydroxide solution: Ca(OH)₂ + 2HCl → CaCl₂ + 2H₂O.
[4 marks] - 25.
A strong acid of pH 2 is diluted with water so that its concentration decreases by a factor of 10. State the new pH of the diluted acid, and explain your reasoning in terms of hydrogen ion concentration.
[3 marks] · no calculator