It is possible that ores containing basic copper(II) carbonate also contain water of crystallisation. The formula of these ores would be written as xCuCO3•yCu(OH)2•zH2O. In this experiment you will heat a sample of a different basic copper(II) carbonate which will thermally decompose as shown. xCuCO3•yCu(OH)2•zH2O(s) → (x+y)CuO(s) + xCO2(g) + (y+z)H2O(g) You will use your results to determine whether this sample of a different basic copper(II) carbonate contains water of crystallisation. FA 3 is a sample of a different basic copper(II) carbonate.

1. (a)Method • Weigh the empty crucible with its lid and record the mass. • Add all the FA 3 to the crucible. • Reweigh the crucible, lid and FA 3. Record the mass. • Support the crucible in the pipeclay triangle on top of the tripod. • Remove the lid. • Heat the crucible gently for about 1 minute and then strongly for about 4 minutes. • Replace the lid and allow the crucible to cool. • You may wish to start Question 3 while the crucible is cooling. • When the crucible has cooled, reweigh the crucible, lid and contents. Record the mass. • Calculate and record the mass of FA 3 used, the mass of residue and the loss of mass. Results[6]
2. (b)(i)Assume the percentage by mass of copper(II) carbonate in FA 3 is 60.0%. Calculate the mass of copper(II) carbonate present in FA 3. mass of CuCO3 = ...................................... g Hence calculate the number of moles of copper(II) carbonate in FA 3. moles of CuCO3 = ...................................... mol[1]
3. (b)(ii)Use your results from (a) to calculate the number of moles of copper(II) oxide formed on heating FA 3. moles of CuO = ...................................... mol[1]
4. (b)(iii)Use your answers to (i) and (ii) and the equation on page 5 to calculate the number of moles of copper(II) hydroxide in FA 3. moles of Cu(OH)2 = ...................................... mol[1]
5. (b)(iv)Use your answer to (i) to calculate the mass of carbon dioxide produced by the thermal decomposition of the copper(II) carbonate in FA 3. mass of CO₂ = ...................................... g[1]
6. (b)(v)Use your answer to (iii) to calculate the mass of water produced by the thermal decomposition of the copper(II) hydroxide in FA 3. mass of H2O = ...................................... g[1]
7. (b)(vi)Deduce whether water of crystallisation is present in basic copper(II) carbonate FA 3. Justify your answer using your results from (a) and your answers to (iv) and (v).[1]
8. (c)(i)The lid was replaced before the crucible was cooled. Explain how replacing the lid before the crucible was cooled may have increased the accuracy of your results.[1]
9. (c)(ii)Using the same apparatus, suggest an improvement to the method to increase the accuracy of your results.[1]
10. (c)(iii)A student carried out the method in (a) and obtained inaccurate results. The student suggested that not all of the copper(II) carbonate in the sample of basic copper(II) carbonate FA 3 had thermally decomposed. Suggest a chemical test to determine whether the student was correct. Give the expected observations. Do not carry out this test.[1]