OCR A Jun 2016 Paper 1 Q4

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10 This question is about the chemistry of the metals zinc, magnesium, aluminium and calcium. (a) Complete the electron configuration of a zinc atom. 1s2[1] (b) A sample of zinc was found to contain four isotopes with the abundances shown in the table. Isotope Abundance (%) 64Zn 66Zn 67Zn 68Zn 49.0 27.9 4.3 18.8 (i) Define the term relative atomic mass.[3] (ii) Calculate the relative atomic mass of zinc in this sample. Give your answer to two decimal places. relative atomic mass of zinc =[2]OCR 2016<br />
 (c) Zinc carbonate, ZnCO3, reacts with dilute hydrochloric acid. 11 A student reacts a sample of ZnCO3 with an excess of dilute hydrochloric acid in a test-tube. (i) Describe what the student would see during this reaction.[1] (ii) Write the equation for the reaction between ZnCO3 and dilute hydrochloric acid.[1] (d) Magnesium will undergo redox reactions with aqueous salts of less reactive metals. (i) A student reacts magnesium with aqueous copper(II) sulfate. Mg(s) + CuSO4(aq) Cu(s) + MgSO4(aq) Explain, in terms of numbers of electron transferred, the redox processes taking place in this reaction.[2] (ii) The student also noticed that the magnesium started fizzing. The student thought the fizzing was due to the magnesium reacting with water in the mixture. Write the equation for the reaction of magnesium with water. Include state symbols.[2]OCR 2016 Turn over<br />
 (e) A student reacts 35.0 cm3 of 3.00102 mol dm3 H2SO4(aq) with an excess of Al. 12 An equation for this reaction is shown. 2Al (s) + 3H2SO4(aq) Al2(SO4)3(aq) + 3H2(g) Calculate the mass, in g, of Al2(SO4)3 formed in solution. Give your answer to three significant figures. Show your working. mass =g [4] (f) Compounds of calcium have many uses. (i) Identify a compound of calcium that could be used to convert a soil pH from 5.8 to 7.5.[1] (ii) Calcium phosphide, Ca3P2, is an ionic compound used in rat poison. Calcium phosphide can be prepared by reacting calcium metal with phosphorus, P4. Write the equation for the reaction of calcium with phosphorus to form calcium phosphide.[1]OCR 2016<br />
 (iii) Draw a dot-and-crossdiagram to show the bonding in calcium phosphide, Ca3P2. Show outer electrons only. 13 [2] [Total: 20] END OF QUESTION PAPEROCR 2016<br />

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