25) The set-up shown below is used to study the reaction between magnesium and steam.a) Name the apparatus labelled X and Y.b) Explain why the damp mineral wool is heated.c) Write the chemical equation for the reaction between magnesium and d) Name ONE metal which does not react when heated with steam.(g) (1)steam.X: delivery tube (1) Y: gas jar (1)To generate steam. (1)Mg(s) + H2O(g) MgO(s) + H2Copper / silver / gold / platinum (1)
Jing Kung Educational Press All Rights Reserved80Unit 13 Corrosion of metals and their protectionTopic Exercise (p.134)26) An investigation was carried out to investigate how the following metals react with water and dilute hydrochloric acid:calcium copper magnesium zincroom temperature.hydrochloric acid.dilute hydrochloric acid.reactivity.Calcium (1)Hydrogen (1)Copper (1)calcium > magnesium > zinc > copper (1)
Jing Kung Educational Press All Rights Reserved81Unit 13 Corrosion of metals and their protectionTopic Exercise (p.134)27) Water pipes used to carry drinking water are commonly made of copper instead of iron. Although lead-containing solder can be used to join these water pipes, such use is prohibited.than iron for making water pipes. Explain your answer.ii) Explain why lead-containing solder is prohibited in joining these water pipes.(HKDSE, Paper 1B, 2017, 2(a)–(b))Answers for the questions of the public examinations in Hong Kong are not provided (if applicable).
Jing Kung Educational Press All Rights Reserved82Unit 13 Corrosion of metals and their protectionTopic Exercise (p.134)28) A student studied the reaction of water with two Group II metals, calcium and barium.a beaker.i) Write the chemical equation for the reaction involved.ii) Draw a labelled diagram of an experimental set-up for carrying out this reaction in a beaker and collecting the gas produced.iii) Suggest ONE potential hazard in performing the reaction.Ca(s) + 2H2O(l) Ca(OH)2(s) + H2Any one of the following:• Hydrogenproduced was flammable/ can explode. (1)• A lot ofheat was released. (1)
Jing Kung Educational Press All Rights Reserved83Unit 13 Corrosion of metals and their protectionTopic Exercise (p.134)b) The student repeated the reaction using the same mass of barium. She noticed that the volume of gas collected, still at the same temperature and pressure, was less.It was known that at constant temperature and pressure, the volume of a gas was proportional to the number of moles present.