Metal Reactions and Reactivity

1. Metal Reactions and Reactivity Reactivity series Metals and acids Displacement Metal oxides and acids Metal carbonates and acids Metals and oxygen Metals and water Extraction

2. Investigating Metals 1. Collect five test tubes and fill each test tube with an equal amount of hydrochloric acid (a couple of centimetres). • 2. To each test tube add a sample of the five metals listed: zinc, copper, lead, iron, magnesium. • 3. Record your observations in the table below. What could you see in the test tubes? Which metal was the most reactive? Which metal was the least reactive? Reacts Gas bubbles No reaction Very slow reaction Slow reaction Magnesium Reacts vigorously Copper

3. Reactivity Results Even though they are all metals and share a lot of common properties, they react to different extents with dilute acid. Copper does not react at all whereas magnesium is very reactive. Copper Lead Iron Zinc Magnesium Reactivity increases Least reactive Most reactive We can order the metals from ‘least reactive’ to ‘most reactive’ in a REACTIVITY SERIES.

4. The Reactivity Series K Na Li Reacts with dilute acid. Ca Where hydrogen fits in the reactivity series. Mg Al Zn Fe Sn Reactivity increases Pb Do not react with dilute acid. Cu Potassium is the most reactive and platinum is the least reactive. Ag Au Pt

5. Displacement Reactions 1 An element higher in the reactivity series will displace an element lower than it from a compound. The more reactive element will take the place of the less reactive element. Out the way, copper! If you add magnesium to copper sulphate solution the magnesium will displace the copper; forming magnesium sulphate and copper. Mg Cu SO4 Mg SO4 Cu + + Magnesium + Copper sulphate  Magnesium sulphate + Copper Mg + CuSO4 MgSO4 + Cu

6. Displacement Reactions 2 An element higher in the reactivity series will not be displaced by an element lower than it from a compound. The more reactive element will stay in the compound. No way, copper! If you add copper to magnesium sulphate solution the copper will not be able to displace the magnesium. Out the way, magnesium! Cu Mg SO4 Mg SO4 Cu + + Copper + Magnesium sulphate  No reaction

7. Acids and Metals Metals can react with dilute acid to form their salts and hydrogen gas. Lead upwards in the reactivity series will react with dilute acid. Copper, silver, gold and platinum will not react with dilute acid. Potassium, sodium and lithium react explosively, so we avoid using them. Example Magnesium + Hydrochloric acid  Magnesium chloride + Hydrogen You must also be able to represent the formula using symbols… Mg + 2HCl  MgCl2 + H2 ..and particles. + +

8. Exercise 1: Complete the Blanks 1. Magnesium + ____________ Magnesium chloride + Hydrogen 2. _________ + Nitric acid  Aluminium nitrate + Hydrogen 3. Calcium + Hydrochloric acid  Calcium chloride + _________ 4. Zinc + Sulphuric acid  _____________ + Hydrogen Hydrochloric acid Aluminium Hydrogen Zinc sulphate

9. Exercise 2: Chemical Formula 1. Magnesium + Nitric acid Magnesium nitrate + Hydrogen 2. Calcium + Hydrochloric acid  Calcium chloride + Hydrogen 3. Iron + Hydrochloric acid  Iron chloride + Hydrogen 4. Aluminium + Sulphuric acid  Aluminium sulphate + Hydrogen Mg + 2HNO3 Mg(NO3)2 + H2 Ca + 2HCl  CaCl2 + H2 Fe + 2HCl FeCl2+ H2 2Al + 3H2SO4 Al2(SO4)3+ 3H2

10. Acids and Metal Carbonates Metal carbonates react with acids to form salts, carbon dioxide and water. Example Zinc carbonate + Nitric acid  Zinc nitrate + Carbon dioxide + Water Do you know the chemical equation for the word equation above? ZnCO3 + 2HNO3  Zn(NO3)2 + CO2 + H2O What is the chemical test for carbon dioxide? If you bubble carbon dioxide through limewater, the limewater will turn milky and then clear again.

11. Exercise 3: Complete the Blanks • 1. Magnesium carbonate + ________ Magnesium nitrate + Water • + Carbon dioxide • 2. Zinc carbonate + Hydrochloric acid Zinc chloride + Water • + ____________ • 3. _______________ + Nitric acid Calcium nitrate + Water • + Carbon dioxide • 4. Aluminium carbonate + ____________ Aluminium sulphate + Water + Carbon dioxide Nitric acid Carbon dioxide Calcium carbonate Sulphuric acid

12. Exercise 4: Metal Reactions 1. What are the products when hydrochloric acid is added to magnesium? 2. What are the products when sulphuric acid is added to calcium carbonate? 3. What is the chemical test for hydrogen? 4. What is the chemical equation when calcium carbonate is added to hydrochloric acid? Magnesium chloride and hydrogen Calcium sulphate, carbon dioxide and water Hydrogen gas will cause a ‘popping’ sound when a lit spill is brought near it CaCO3 + 2HCl  CaCl2 + H2O + CO2

13. Acids and Metal Oxides Metal oxides (bases) react with acids to form a salt and water. ACID + METAL OXIDE  SALT + WATER Example: Zinc oxide + Hydrochloric acid  Zinc chloride + Water Do you know the chemical equation for the word equation above? ZnO + 2HCl ZnCl2 + H2O What do we call a base that is soluble in water? An alkali

14. Exercise 5: Metal Oxides and Acids 1. What are the products when sulphuric acid is added to copper oxide? 2. What colour is copper sulphate in solution? 3. What are the products when sulphuric acid is added to zinc oxide? 4. What is the chemical equation when sulphuric acid is added to zinc oxide? Copper sulphate and water Blue Zinc Sulphate and water H2SO4 + ZnO  ZnSO2 + H2O

15. How do the following react with steam? Metals & Water Whether a metal reacts with water or not depends upon its position in the reactivity series. Explode with steam. React with steam giving metal oxide and hydrogen. Very little reaction with steam. No reaction.

16. Water and K, Na, Li and Ca These four reactive metals react with water to form the metal hydroxide (which is alkaline) and hydrogen. If reacted with steam they EXPLODE! Metal + Water  Metal hydroxide + Hydrogen Example Calcium + Water  Calcium hydroxide + Hydrogen Ca + H2O  Ca(OH)2 + H2 What is the chemical formula for potassium hydroxide? KOH What colour would KOH turn litmus solution? Blue

17. Water and Mg, Al, Zn and Fe These four metals react with water very slowly. However, if heated with steam, they react a lot faster to produce the metal oxide and hydrogen. Metal + Steam  Metal oxide + Hydrogen Example Zinc + Steam  Zinc oxide + Hydrogen Zn + H2O  ZnO + H2 Al2O3 What is the chemical formula for aluminium oxide?

18. The Reactivity Series and Burning in Air K Na Li Burn to form oxides Ca Mg Forms outer oxide layer, no burning Al Zn Fe Reactivity increases Sn Pb Do not burn in air Cu Examples Lithium + Oxygen  Lithium oxide Gold + Oxygen  No reaction Ag Au Pt

19. Exercise 6: Reacting Metals With Air Only the more reactive metals will burn in air to form the oxide. Which equations are correct for metals burning in air? 1. Potassium + Oxygen  Potassium oxide 2. Magnesium + Oxygen  No reaction 3. Gold + Oxygen  Gold oxide 4. Silver + Oxygen  Silver dioxide 5. Zinc + oxygen  Zinc oxide 6. Aluminium + oxygen  Aluminium oxide 7. Gold + oxygen  No reaction  x x x   

20. Extraction of Metals There are many different metals that are used by humans. Where do they come from? We get them from the ground. Some metals are found on their own as an element, we say they are NATIVE. It is only the UNREACTIVE metals such as GOLD that are found native. Most metals are not found native, they are TOO REACTIVE and have formed compounds with other elements. We call these metal compounds ORES. Iron is found as an ore called HAEMATITE. A miner ‘panning’ for gold

21. Exercise 7: Why is Gold Found Native and Not in an Ore? Gold is an unreactive element; this means it will not react with other elements to form ores.

22. Extraction Methods The method of extracting a metal from its ore depends upon HOW REACTIVE the metal is. The more reactive the metal, the MORE DIFFICULT (and EXPENSIVE) it is to separate it from its ore. • The three main methods of extraction are: • Heating in air. • Heating with carbon. • Electrolysis. 12 C 6 Which method you use to separate a metal from its ore depends upon the position of the metal in the reactivity series. Mainly, it depends whether THE METAL IS MORE OR LESS REACTIVE THAN CARBON. If the metal is less reactive than carbon, carbon can displace the metal from its compound.

23. Extraction Methods K Electrolysis Na Li Ca Carbon Mg Heating with carbon Al Zn Reactivity increases Fe Burning in air Sn Pb Cu Electrolysis is very expensive, thus, the cheapest possible method is always used. Carbon would appear between Zn and Al in the reactivity series. Ag Found native Au Pt

24. Exercise 8: Extracting Metals 1. What is the difference between an ore and a native element? 2. Give an example of a native element. 3. Name three methods of extraction. 4. How would you obtain aluminium from its ore bauxite? 5. How would you obtain lead from its ore galena? A native element is un-reactive and found on its own. An ore is a compound of a more reactive metal element with other elements. Gold. Heating in air, reducing with carbon, electrolysis. Using electrolysis. Reducing it with carbon.