HKCEE Chemistry Past Paper fossil fuels - 1842 Words

CE : Section 5 Fossil Fuels 1. 93 1(c) Alkenes can be obtained from petroleum fractions by a process called cracking’. Using a suitable petroleum fraction, a student carried out this process in the laboratory and collected the gaseous product over water. (i) What is cracking’ ? (ii) Draw a labelled diagram of a laboratory set-up that can be used for carrying out the process and collecting the gaseous product. (iii) An important safety precaution in the experiment is to prevent sucking back. (1) What is the potential hazard if sucking back occurs ? (2) How can sucking back be prevented ? (iv) If the gaseous product decolorizes a solution of bromine in tetrachloromethane, can you conclude that the gaseous product in ethene†¦show more content†¦(i) Suggest what solution X may be. (ii) (1) Write an ionic equation for the reaction between solution X and the sodium hydrogencarbonate solution. (2) Explain why a jet of aqueous solution is forced out of the extinguisher. (iii) The diagram below shows a fire triangle. (1) Complete the fire triangle by writing a suitable word for Y. (2) Using the concept of fire triangle, give TWO reasons why the fire extinguisher mentioned previously can be used to put out a fire. (iv) In the Mass Transit Railway, bromochlorodifluoromethane (BCF) fire extinguisher, rather than the type of fire extinguisher shown on the previous page, is used to put out electrical fire. Suggest ONE advantage and ONE disadvantage of using a BCF fire extinguisher to put out electrical fire. (8 marks) 8. 97 5 In March 1989, the oil tanker Exxon Valdex was wrecked off the coast of Alaska and spilt a large amount of crude oil into the sea. The oil spillage caused serious environmental problems. Briefly explain why oil spillage in the sea can cause serious environmental problems and suggest ONE method of treating the spilt oil. (8 marks) 9. 97 9(a) The photograph below shows a gas burner with a can of fuel. The can contains 250 g of liquefied butane. (i) Write the structural formula of butane. (ii) (1) Write the chemical equation for the complete combustion of butane. (2) Suggest a chemical test for EACH