- W -water aboratory e thermal W is hy is nitric potassium sulphuric sulphur purity in NH₂(9) 566 gas furnace calcium oxide cold water- copper oxide powder UN 1. a) i) Why is calcium chloride not a suitable replacement for the calcium oxide? State the function of the calcium oxide as shown on the diagram. ii) iii) Assuming that oxidation / reduction takes place in the tube in the furnace, name the substance which is oxidized. b) Briefly describe the colour change that will be observed in the content of the tube in the furnace as the reaction goes from start to finish. c) What are the products X and y? d) Write an equation for the reaction taking place in the tube in the furnace. Describe a simple test that could be carried out to confirm the identity of X.