9. Metals
A section of Chemistry, 0620
Listing 10 of 1272 questions
Use The list shows part of the reactivity series. strontium calcium magnesium iron copper more reactive less reactive Calcium is manufactured by the electrolysis of molten calcium chloride. Suggest why calcium is extracted by electrolysis. Equal sized pieces of magnesium, strontium and calcium are placed in water. Some observations about these reactions are shown in the table. Complete the box for strontium. metal observations magnesium Gives off a few bubbles of gas with hot water. Dissolves very slowly. calcium Gives off bubbles steadily with cold water. Dissolves slowly. strontium When water is added to calcium carbide, acetylene and calcium hydroxide are formed. State a use for acetylene. A solution of calcium hydroxide is alkaline. Complete and balance the equation for the reaction of calcium hydroxide with hydrochloric acid. Ca(OH)2 + 2HCl CaCl2 + What type of chemical reaction is this? Examiner's Use A student used the apparatus shown below to calculate the concentration of a solution of calcium hydroxide. calcium hydroxide solution hydrochloric acid A State the name of the piece of apparatus labelled A. Describe how the pH of the solution in the flask changes as the hydrochloric acid is added.
0620_w06_qp_2
THEORY
2006
Paper 2, Variant 0
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The reactions of a metal and the thermal stability of some of its compounds are determined by the position of the metal in the reactivity series. To fi nd the order of reactivity of the metals, cobalt, magnesium, silver and tin, the following experiments were carried out. experiment result tin plus silver(nitrate solution silvery layer on tin magnesium plus tin(nitrate solution grey deposit on magnesium tin plus cobalt nitrate solution no reaction Give as far as possible the order of reactivity of these metals. Write the least reactive fi rst. What additional experiment needs to be done to put all four metals in order of reactivity? Write an ionic equation for the reaction between tin atoms and silver(ions. Indicate on the equation the change which is oxidation. Sodium is a more reactive metal than magnesium. Sodium compounds are more stable than magnesium compounds. In an experiment, their hydroxides were heated. If the hydroxide did not decompose write ‘no reaction’ otherwise complete the equation. NaOH → Mg(OH)2 → A cell consists of two different metal electrodes in an electrolyte. Three possible cells are shown below. V zinc copper dilute acid 1.1 V V tin dilute acid 0.5 V V zinc tin dilute acid V + – + – Why is the more reactive metal the negative electrode? How can you deduce that zinc is more reactive than tin? How could you change the zinc/copper cell to have a voltage greater than 1.1 V? Complete the labelling of the zinc/tin cell.
0620_w10_qp_33
THEORY
2010
Paper 3, Variant 3
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The table describes the reactivity of some metals with hydrochloric acid. metal observations calcium Many bubbles produced. Reaction mixture may boil. magnesium Steady stream of bubbles produced. Reaction mixture gets hot. sodium Many bubbles produced. May explode. zinc Slow stream of bubbles produced. Reaction mixture rises slightly in temperature. Put these metals in order of their reactivity. least reactive most reactive Complete the word equation for the reaction of magnesium with hydrochloric acid. magnesium + hydrochloric acid → + When magnesium reacts with hydrochloric acid, magnesium atoms lose electrons. What type of magnesium particle is formed? Put a ring around the correct answer. covalent ion molecule proton Complete the diagram to show the electronic structure of a sodium atom. Na A student added large lumps of zinc to 20 cm3 of 2 mol / dm3 hydrochloric acid. She carried out the reaction at 15 °C. She measured the volume of gas given off at various time intervals. Draw a labelled diagram of the apparatus she could use for this experiment. Describe three different things she could do to increase the rate of this reaction. 1. 2. 3.
0620_w13_qp_22
THEORY
2013
Paper 2, Variant 2
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The following reactivity series shows both familiar and unfamiliar elements in order of decreasing reactivity. Each element is represented by a redox equation. Rb Rb+ + e– Mg Mg2+ + 2e– Mn Mn2+ + 2e– Zn Zn2+ + 2e– H2 2H+ + 2e– Cu Cu2+ + 2e– Hg Hg2+ + 2e– Two of the uses of the series are to predict the thermal stability of compounds of the metals and to explain their redox reactions. Most metal hydroxides decompose when heated. Complete the equation for the thermal decomposition of copper(hydroxide. Cu(OH)2 → + Choose a metal from the above series whose hydroxide does not decompose when heated. Defi ne in terms of electron transfer the term oxidation. Explain why the positive ions in the above equations are oxidising agents. Which metals in the series above do not react with dilute acids to form hydrogen? Describe an experiment which would confi rm the prediction made in . Which metal in the series above can form a negative ion which gives a pink / purple solution in water? Describe what you would observe when zinc, a reducing agent, is added to this pink / purple solution.
0620_w13_qp_32
THEORY
2013
Paper 3, Variant 2
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Questions Discovered
1272