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Metals - Reactivity Series
- 1. Last Lesson… METALS: The Physical Properties of Metals
- 2. Physical properties of metals METALS Solid state at room temp Shiny appearance High density Good heat conductors Good conductors of electricity High Melting and Boiling point Ductile and malleable Strong and tough Except Mercury (Liquid) Due to strong forces (metallic) except Mercury and alkali metals Due to the presence of mobile ions Can be bent and stretched without breaking Atoms are closely packed Due to the presence of mobile ions
- 3. Metals and Alloys Iron Carbon LEGEND: Pure Iron Metal Steel (Alloy) Using the diagram above, explain why alloys are harder and stronger than pure metals? In alloy, the layers of atoms cannot slide over each other easily A mixture of 2 or more metals
- 4. Chapter 9:METALS METALS: The Reactivity Series
- 5. At the end of the lesson, students should be able to Describe the reactions, if any between some metals (in the reactivity series) with water Describe the reactions, if any between some metals (in the reactivity series) with steam Describe the reactions, if any between some metals (in the reactivity series) with dilute acid Rank the metals in order of their reactivity Objectives (1)
- 6. Describe the reduction reactions, if any, of the metal oxides with carbon Describe the reduction reactions, if any, of the metal oxides with hydrogen Describe the action of heat on the metal carbonates and relate thermal stability to the reactivity series At the end of the lesson, students should be able to Objectives (2)
- 7. METALS CHEMICAL PROPERTIES PHYSICAL PROPERTIES have REACTIVITY OF METALS includes REACTIVITY SERIES Arranged in Most reactive Least reactive Dilute acids Cold water Steam Determined by the reaction Discussed in last lesson Reduction of metal oxides Decomposition of metal carbonates An Overview
- 8. By experimental observations in the laboratory which includes: - Reaction of metals with cold water - Reaction of metals with steam - Reaction of metals with dilute acid Using the reactivity series obtained from the above experimental observations enable: - Prediction of reaction between metal oxides with carbon or hydrogen - Prediction of action of heat on metal carbonates The order of reactivity
- 9. Metals I II III IV V VI VII O 11 Fe 26 Cu Zn 30 29 Ag 47 Na 11 Mg 12 K 19 Ca 20 Pb 82 H 1
- 10. R E A C T I V I T Y MOST REACTIVE METAL LEAST REACTIVE METAL Potassium (K) Sodium (Na) Calcium (Ca) Magnesium (Mg) Zinc (Zn) Iron (Fe) Lead (Pb) (Hydrogen) Copper (Cu) Silver (Ag) P lease S end C ats M onkeys Z ebras I nto L ovely H appy C ages S oon Non-metal Reactivity Series
- 11. MOST REACTIVE METAL P lease S end C ats M onkeys A nd Z ebras I n L arge H ired C ages M ake S ure P roperly G uarded Potassium (K) Sodium (Na) Calcium (Ca) Magnesium (Mg) Aluminium (Al) Zinc (Zn) Iron (Fe) Lead (Pb) (Hydrogen) Copper (Cu) Mercury (Hg) Silver (Ag) Platinum (Pt) Gold (Au) R E A C T I V I T Y LEAST REACTIVE METAL
- 12. For Example: Reaction of Metals with Water Some metals react chemically with cold water - Metal hydroxide is formed - Hydrogen gas liberated Metal + Water Metal hydroxide + Hydrogen Using Experimental Observations Determination of Reactivity Series
- 13. Apparatus Hydrogen gas Cold water Filter funnel Metal
- 14. Aqueous Potassium hydroxide is formed Hydrogen gas liberated Reaction of Potassium with cold water 2K(s) + 2H 2 O(l) 2KOH (aq) + H 2 (g) Potassium + Water Potassium hydroxide + Hydrogen gas Violent reaction; may explodes with water Cold water K K Hydrogen gas Red litmus turn blue Aqueous Potassium hydroxide Hydrogen gas can burn in air Potassium darted around on the surface of water Hydrogen gas given off and a alkaline solution formed
- 15. Water Aqueous Potassium hydroxide Hydrogen gas Violent reaction Testing of hydrogen gas: Lighted splint goes off with a ‘pop’ sound Potassium Test for hydrogen gas “ POP”
- 16. Reaction is very slow A few bubbles of hydrogen gas is produced only Reaction of Magnesium with cold water 2Mg(s) + 2H 2 O(l) 2Mg(OH) 2 (aq) + H 2 (g) Magnesium + Water Magnesium hydroxide + Hydrogen gas Reaction is too slow! Petri dish Top view of Petri dish Magnesium ribbon Bubbles of H 2 gas
- 17. No reaction Reaction of Zinc with cold water Zn (s) + H 2 O(l) No reaction Zinc Water Petri dish Top view of Petri dish No reaction
- 18. Table 1: Reaction of Metals with cold water Reactivity of metals increase up the series No reaction occurs Zinc Iron Lead Copper Silver Reacts very slowly with cold water A few bubbles of hydrogen gas produced only Magnesium Reacts readily Hydrogen gas formed Ca(s) + 2H 2 O(l) Ca(OH) 2 (aq) + H 2 (g) Calcium Reacts violently Hydrogen formed may catch fire and explode 2Na(s) + 2H 2 O(l) 2NaOH(aq) + H 2 (g) Sodium Reacts very violently; explodes with cold water Enough heat is produced to ignite the hydrogen gas produced Hydrogen gas burn in air 2K(s) + 2H 2 O(l) 2KOH (aq) + H 2 (g) Potassium Observations/Equations Metal
- 19. Reaction of Metals with Steam The metal is heated A glass wool is heated to generate a flow of steam over the hot metal Metals like Zinc and Iron do not react with cold water but react with steam Magnesium react violently with steam but react slowly with cold water Hydrogen gas is liberated Metal oxide formed
- 20. Violent reaction Magnesium oxide (white powder) and hydrogen produced Bright white glow produced during the reaction Reaction of Magnesium with Steam Mg (s) + H 2 O(g) MgO (s) + H 2 (g) Magnesium + Steam Magnesium oxide + Hydrogen gas Reaction is vigorous! Hydrogen gas burn in air Glass wool soaked with water Heat to produce steam Magnesium ribbon is heated; bright white glow produced
- 21. Apparatus Hydrogen gas Glass wool soaked in water Metal Heat Heat Water
- 22. Table 2: Reaction of Metals with Steam Reactivity of metals increase up the series No reaction with cold water Lead Copper Silver Reacts slowly with steam Tri-iron tetroxide and hydrogen produced Reaction is easily reversible; so iron need to be heated constantly for reaction to take place 3Fe (s) + 4H 2 O (g) Fe 3 O 4 (s) + 4H 2 (g) Iron Burns in steam Zinc oxide (yellow when hot and white when cold) and hydrogen produced Zn (s) + H 2 O (g) ZnO (s) + H 2 (g) Zinc Reacts violently with steam Magnesium oxide (white powder) and hydrogen produced Bright white glow produced during the reaction Mg (s) + H 2 O (g) MgO (s) + H 2 (g) Magnesium Observations/Equations Metal
- 23. K > Na > Ca > Mg > Zn > Fe > Pb > Cu > Ag Increasing reactivity Decreasing reactivity Using Experimental Observations Reactivity of Metals
- 24. Reaction of Metals with dilute acid For example, dilute hydrochloric acid (HCl) Many metals react with dilute acids to produce (i) salt and (ii) hydrogen gas Metal + Dilute acid Salt + Hydrogen gas When dilute hydrochloric acid is used, the products are (i) Metal chloride (salt) (ii) Hydrogen gas
- 25. Demonstration Time! Given 3 unknown Metal X, Y and Z Metal X Metal Y Metal Z 3 unknown metals will each be added into a test tube filled with 1/3 dilute hydrochloric acid respectively Observe the reactions, if any
- 26. Metal X Test tube 1 Test tube 2 Test tube 3 Metal Y Metal Z Arrange the reactivity of the metals (starting with the most reactive) with reference to the observations in the demonstration. Predict a suitable identity for Metal X, Y and Z
- 27. Table 3: Reaction of Metals with dilute hydrochloric acid Reactivity of metals increase up the series; metals on top of the series reacted more readily and violently with dilute acids Reacts moderately fast to give hydrogen and zinc chloride Zn (s) + 2HCl (aq) ZnCl 2 (aq) + H 2 (g) Zinc No reaction occurs Lead Copper Silver Reacts very slowly to produce hydrogen and iron (II) chloride Fe (s) + 2HCl (aq) FeCl 2 (aq) + H 2 (g) Iron Reacts rapidly to give hydrogen and magnesium chloride Mg (s) + 2HCl (aq) MgCl 2 (aq) + H 2 (g) Magnesium Reacts violently to give hydrogen and calcium chloride Ca (s) + 2HCl (aq) CaCl 2 (aq) + H 2 (g) Calcium Explosive reaction Should not be carried out in school laboratory 2K (s) + 2HCl (aq) 2KCl (aq) + H 2 (g) 2Na (s) + 2HCl (aq) 2 NaCl (aq) + H 2 (g) Potassium Sodium Observations/Equations Metal
- 28. Question to ponder! If dilute sulphuric acid (H 2 SO 4 ) is used instead of dilute hydrochloric acid (HCl) for reaction with the metals. Predict what you will observe and the products formed if any.
- 29. Summary table of the reactivity of the metals from experimental observations Reactive metals Fairly reactive metals Unreactive metals Hydrogen gas is produced in all three reactions Reactive metals tend to react with non-metals to form compounds Unreactive metals have a greater tendency to remain uncombined No reaction No reaction with water and steam Lead Copper Silver Moderately fast reaction Slow reaction React with steam Magnesium Zinc Iron Explosive reaction Violent reaction React with cold water Potassium Sodium Calcium Reaction with dilute acids Reaction with water or steam Metal
- 30. Review 1 Increasing reactivity Least reactive metal Most reactive metal K Mg Cu Na Ca Zn Pb Fe Ag List the products formed when hot Zinc reacts with steam. Zinc oxide Hydrogen gas Write a balanced equation to show the reaction of calcium with water. Ca (s) + 2H 2 O (l) Ca(OH) 2 (aq) + H 2 (g)
- 31. Metals Reactivity Water Decomposition of metal carbonates Reduction of metal oxides Dilute acids Steam Recall… Arranged via Determined by reaction with
- 32. MgO (s) + C (s) No reaction 2CuO (s) + C (s) 2Cu (s) + CO 2 (g) Copper oxide reduced to copper Reduction of metals oxides with carbon Can be used to compare the reactivity of the metals The more reactive a metal is, the more difficult to split up its oxides Magnesium oxide was not reduced Magnesium being a more reactive metal than copper in the reactivity series, its oxides did not decompose when heated Increasing reactivity Can be tested using limewater K > Na > Ca > Mg > Zn > Fe > Pb > Cu > Ag
- 33. Apparatus Mixture of metal oxides and carbon Wire gauze
- 34. Importance of this reaction (Metal oxides with Carbon) Metals below magnesium in the reactivity series can be reduced by carbon - Metals can be extracted from their ores by reduction with carbon - Includes metals from Zinc to Silver in the reactivity series Oxides of metals above Zinc in the reactivity series cannot be reduced by carbon - These metal oxides are very stable - Reduced by electrolysis
- 35. Reduction of metal oxides with hydrogen Hydrogen gas passed over metal oxides - H 2 acts as a reducing agent - H 2 reduced metal oxides to its metal For example: Fe 2 O 3 (s) + 3H 2 (g) 2Fe (s) + 3H 2 O (l) Metals above Iron in the reactivity series, their oxides are not reduced by hydrogen
- 36. Apparatus Heat Metal oxides Hydrogen
- 37. Summary table of the reductions of metal oxides with carbon and hydrogen Heated metal oxides are not reduced Heated metal oxides are reduced Heated metal oxides are not reduced Heated metal oxides are reduced Potassium oxide (K 2 O) Sodium oxide (Na 2 O) Calcium oxide (CaO) Magnesium oxide (MgO) Zinc oxide (ZnO) Iron (III) oxide (Fe 2 O 3 ) Lead (II) oxide (PbO) Copper (II) oxide (CuO) Silver (I) oxide (Ag 2 O) Reduction with hydrogen Reduction with carbon Metal oxide
- 38. Important to note! Metal atoms react with non-metallic elements or compounds to form metal ions Metal atom Metal ion + Electron Reactivity of a metal depends on the ease with which it forms metal ions - A metal that is higher up in the reactivity series has a higher tendency to form its positive ions Increasing reactivity and tendency to form positive ions K > Na > Ca > Mg > Zn > Fe > Pb > Cu > Ag
- 39. Action of heat on metal carbonates Some compounds are more stable than others - more difficult to be decompose by heat Thermal stability of metal carbonates can be tested by heating them in a dry test-tube - The more reactive a metal is, the more difficult it is to decompose its compound; the more thermal stable it is - Potassium carbonate and sodium carbonate are heat stable - Carbonates of metals below sodium in the reactivity series decompose to: oxides of the metal and carbon dioxide Metal carbonates Metal oxides + carbon dioxide Heat
- 40. Apparatus Limewater: To test for carbon dioxide gas Metal carbonate
- 41. Table of the action of heat on metal carbonates decomposes on heating to give silver oxide, carbon dioxide silver oxide produced is thermally unstable silver oxide further decomposes to silver 2Ag 2 O (s) 2Ag (s) + O 2 (g) silver carbonate decompose on heating to give carbon dioxide gas and the metal oxide metal (heat) metal oxide + carbonate carbon dioxide Calcium carbonate Magnesium carbonate Zinc carbonate Lead carbonate Iron (II) carbonate Copper (II) carbonate No change Potassium carbonate Sodium carbonate Effect of heat on the carbonate Metal carbonates Decomposes more easily down the reactivity series; Thermal stability decreases
- 42. Review 2 Write the chemical equation of the reaction between silver oxide and hydrogen. Ag 2 O (s) + H 2 (g) Ag (s) + H 2 O (l) Arrange the carbonates below according to the ease of decomposition, starting with the most easily decompose carbonate. ZnCO 3 , MgCO 3 , Ag 2 CO 3 , Na 2 CO 3 , Fe 2 CO 3 , CaCO 3 Ag 2 CO 3 , Fe 2 CO 3 , ZnCO 3 , MgCO 3 , CaCO 3 , Na 2 CO 3
- 43. Metals Reactivity Water Decomposition of metal carbonates Reduction of metal oxides Dilute acids Steam Recall… Arranged via Determined by reaction with Displacement reactions in the next lesson
- 44. Displacement reaction Deducing the order of reactivity from a given set of experimental results - Read textbook page 291-296 before next lesson Activity worksheet 1: Reactivity Series (I) Activity worksheet 2: Reactivity Series (II) Next Lesson