1. 1
   A student adds dilute hydrochloric acid to a beaker containing lumps of solid calcium carbonate (marble chips). Fizzing is observed immediately.

   (a)

   Which gas is responsible for the fizzing?

   [1 mark]

   • AHydrogen
   • BOxygen
   • CCarbon dioxide
   • DChlorine

   (b)

   Which salt is formed when calcium carbonate reacts with hydrochloric acid in this reaction?

   [1 mark]

   • ACalcium chloride
   • BCalcium nitrate
   • CCalcium sulfate
   • DCalcium carbonate (unchanged)

   (c)

   Write the word equation for the reaction between calcium carbonate and hydrochloric acid, and describe a test the student could carry out to confirm the identity of the gas produced.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A gardener wants to reduce the acidity of a flower bed's soil. They mix crushed limestone (calcium carbonate) into the soil, where it reacts slowly with dilute acids naturally present in the soil water.

   (a)

   Which two products, besides a salt, are always formed when a metal carbonate reacts with an acid?

   [1 mark]

   • AHydrogen and water
   • BWater and carbon dioxide
   • COxygen and hydrogen
   • DCarbon dioxide and oxygen

   (b)

   If the gardener instead used sulfuric acid to test a small sample of the limestone in a laboratory demonstration, what type of salt would be produced?

   [1 mark]

   • AA chloride
   • BA nitrate
   • CA carbonate
   • DA sulfate

   (c)

   Write a general word equation for the reaction between any metal carbonate and any acid, and explain why this reaction is useful for reducing the acidity of soil.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student is provided with three unlabelled acids: hydrochloric acid, nitric acid and sulfuric acid, and a sample of solid magnesium carbonate. The student adds magnesium carbonate to a portion of each acid in separate test tubes.

   (a)

   Describe what the student would observe in each test tube, and explain why the same type of observation occurs regardless of which acid is used.

   [3 marks]

   (b)

   State the name of the salt produced in each of the three test tubes, and describe a test the student could use to confirm the identity of the gas released in all three reactions.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   An antacid tablet manufacturer includes calcium carbonate as an active ingredient to treat indigestion, which is caused by excess hydrochloric acid in the stomach.

   (a)

   Explain, using chemical equations and ideas about acids and carbonates, how the tablet relieves the symptoms of excess stomach acid.

   [6 marks]

   (b)

   Evaluate why calcium carbonate is a suitable choice for an antacid tablet compared with using a stronger alkali such as sodium hydroxide, considering safety and the practicalities of the reaction with stomach acid.

   [6 marks]

   Total for question 4: 12 marks

End of questions