1. 1
   A student heats a sample of green copper carbonate powder strongly in a test tube using a Bunsen burner. After a few minutes, the powder turns black and a colourless gas is released, which turns limewater cloudy.

   (a)

   Which gas has been released?

   [1 mark]

   • AOxygen
   • BHydrogen
   • CCarbon dioxide
   • DChlorine

   (b)

   What is the name of the black solid remaining in the test tube after the copper carbonate has been heated?

   [1 mark]

   • ACopper metal
   • BCopper oxide
   • CCopper carbonate (unchanged)
   • DCopper hydroxide

   (c)

   Name the type of chemical reaction taking place when copper carbonate is heated, and write a word equation for this reaction.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A technician heats separate samples of magnesium carbonate and sodium carbonate, both to the same high temperature reached by a Bunsen burner. The magnesium carbonate decomposes, but the sodium carbonate does not appear to change.

   (a)

   Why does the sodium carbonate not decompose under these conditions?

   [1 mark]

   • ANot all Group 1 metal carbonates decompose at the temperatures reached by a Bunsen burner
   • BSodium carbonate is not a real compound
   • CSodium carbonate only decomposes in the presence of acid
   • DSodium carbonate cannot exist as a solid

   (b)

   Which two products would be formed if the magnesium carbonate sample described above did fully decompose on heating?

   [1 mark]

   • AMagnesium metal and oxygen
   • BMagnesium chloride and carbon dioxide
   • CMagnesium hydroxide and hydrogen
   • DMagnesium oxide and carbon dioxide

   (c)

   Give the general word equation for the thermal decomposition of a metal carbonate, and name two other metal carbonates (besides magnesium and copper) that decompose in a similar way on heating.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student is given an unlabelled white powder and told it is either calcium carbonate or calcium oxide. The student heats a sample of the powder strongly and passes any gas produced through limewater.

   (a)

   Describe what the student would observe if the powder is calcium carbonate, and explain why this test works.

   [3 marks]

   (b)

   Explain what the student would observe instead if the powder is actually calcium oxide, and describe how the student could use this test to correctly identify an unknown sample.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A quarry produces large quantities of limestone (calcium carbonate), which is heated in industrial kilns to produce quicklime (calcium oxide) for use in construction.

   (a)

   Explain the chemistry of this process, including the type of reaction taking place, the products formed, and why lithium carbonate would behave differently from other Group 1 carbonates if heated in a similar kiln.

   [6 marks]

   (b)

   Discuss why thermal decomposition of limestone is described as an endothermic process, and evaluate the environmental implications of this large-scale industrial process, given that carbon dioxide is released as a by-product.

   [6 marks]

   Total for question 4: 12 marks

End of questions