Quick answer: Acids are substances that release hydrogen ions, H⁺, in water. This Chemistry 9-10 test on acids and bases has 8 questions worth 20 marks, to do in 45 minutes: acid, base or alkali, carbonate and acid and neutralisation ions. The mark scheme is on a separate page; free printable PDF.
This test has eight questions worth 20 marks in total. Write chemical equations carefully, give units where needed and explain in terms of ions where asked. You may use a calculator.
Level: Chemistry grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: GCSE C4, IGCSE 7
Question 1 Acid, base or alkali (2 marks)
- Define an alkali. (1 mark)
- State the pH of a neutral solution and name the ion present in all acids. (1 mark)
Question 2 Carbonate and acid (3 marks)
Sodium carbonate reacts with nitric acid.- Write the word equation. (1 mark)
- Write the balanced symbol equation. (2 marks)
Question 3 Neutralisation ions (2 marks)
- Write the ionic equation for neutralisation of an acid by an alkali. (1 mark)
- In the reaction of potassium hydroxide with nitric acid, name the two spectator ions. (1 mark)
Question 4 Copper chloride crystals (3 marks)
A student makes copper(II) chloride from copper(II) carbonate and dilute hydrochloric acid.- State what is seen when the reaction is finished. (1 mark)
- Explain why the mixture is filtered. (1 mark)
- Explain why the filtrate is not heated until it is dry. (1 mark)
Question 5 Strong and weak acids (3 marks)
Hydrochloric acid and ethanoic acid have the same concentration.- Explain why hydrochloric acid has the lower pH. (2 marks)
- State what the symbol ⇌ shows for ethanoic acid. (1 mark)
Question 6 pH and hydrogen ions (2 marks)
- Calculate how many times more H⁺ ions there are at pH 3 than at pH 5. (1 mark)
- A solution of pH 2 is diluted by adding nine times its volume of water. State the new pH, assuming a strong acid. (1 mark)
Question 7 Reading the pH scale (2 marks)
Use the pH scale of everyday liquids.- State which liquid is the best choice to neutralise an ant sting and name its pH. (1 mark)
- Calculate how many times more H⁺ ions lemon juice has than milk. (1 mark)
Question 8 Antacid tablet (3 marks)
Milk of magnesia contains magnesium hydroxide: Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O (Ar: Mg = 24, O = 16, H = 1, Cl = 35.5).- Calculate the moles in 2.9 g of Mg(OH)₂. (1 mark)
- Calculate the moles of HCl it can neutralise. (1 mark)
- Calculate the mass of MgCl₂ formed. (1 mark)
