REACTIVITY SERIES

Metals and water

Metals and water The Romans used lead to make water pipes but didn’t know that lead reacts slowly with water and makes it poisonous! Some metals react vigorously with water, some metals react slowly and some do not react at all. What is the best type of metal to use for water pipes?

Metals and water – general equation Potassium and sodium are metals that react vigorously with water even when a small amount of each metal is used. When a metal reacts with water, the products are a metal hydroxide and hydrogen gas. What is the general equation for the reaction of a metal with water? metal water metal hydroxide hydrogen What is the test that a metal hydroxide is produced?

Metals and water – equations What are the products when each metal reacts with water? What is the balanced symbol equation for each reaction?  water + lithium lithium hydroxide + hydrogen 2Li + 2H2O  2LiOH H2  water + sodium sodium hydroxide + hydrogen 2Na + 2H2O  2NaOH H2  water + potassium potassium hydroxide + hydrogen 2K + 2H2O  2KOH H2

Metals and water – observations James investigated how reactive some metals are when they react with water and made these observations. Potassium immediately produces a lilac flame as it skims around the surface making a fizzing noise. potassium The sodium melts and skims over the surface producing a stream of small bubbles. Sometimes a yellow-orange flame appeared. sodium Bubbles of gas are given off quite quickly. When tested with universal indicator the water is now alkaline. lithium Metal Reaction with water Which of these metals is the most reactive with water? Which of these metals is the least reactive with water?

Metals and water – more observations James investigated how reactive other metals are with water and made these observations. No reaction. silver copper Reacts slowly with cold water but reacts quickly with steam. magnesium gold Metal Reaction with water Copper is used in plumbing and silver and gold in jewellery. Why are these unreactive metals suitable for such uses?

Metals and water – using unreactive metals The words “plumber” and “plumbing” come from plumbum (the Latin word for lead) because the ancient Romans used lead for their water pipes. Lead reacts very slowly with water making it poisonous, so this metal is no longer used in plumbing. Copper is a much better metal for water pipes because it does not react at all with water – plumbers should be renamed coppers!

Metals and water – order of reactivity Put the following metals in order of reactivity based on their reaction with water, starting with the most reactive: copper, gold, magnesium, lithium, potassium, silver, sodium. potassium sodium lithium magnesium copper, silver, gold

Metals and oxygen

Metals and oxygen – general equation Most metals will react with oxygen. Some metals react faster than others and some may react very slowly or not at all. Magnesium, for example, burns in oxygen with a bright flame. The magnesium reacts with oxygen to produce magnesium oxide. When a metal does react with oxygen, the product is a metal oxide. What is the general equation for the reaction of a metal with oxygen? metal oxygen metal oxide

Metals and oxygen – equations What are the products when each metal reacts with oxygen? What is the balanced symbol equation for each reaction?  oxygen + magnesium magnesium oxide 2Mg + O2  2MgO  oxygen + copper copper oxide 2Cu + O2  2CuO  oxygen + iron iron oxide 4Fe + 3O2  2Fe2O3

Metals and oxygen – observations Shaida investigated how reactive some metals are when they react with oxygen and made these observations. The iron filings glowed red and sparkled leaving a brown-black looking solid. iron The copper turnings went through reds and oranges and then slowly got a permanent coating of black. copper The ribbon burned with a dazzling white flame giving grey-white smoke and ash. magnesium Metal Reaction with oxygen Which of these metals is the most reactive with oxygen? Which of these metals is the least reactive with oxygen?

Metals and oxygen – order of reactivity Put the following metals in order of reactivity based on their reaction with oxygen, starting with the most reactive: copper, iron, magnesium. magnesium iron copper

Metals and acid

Metals and acid – the acid test The first scientists to study chemistry were called alchemists. They were interested in many things including finding ways of changing cheap metals into gold. Some were very good at making metals look gold. Acid was used to find out if gold objects were made of real or fake gold. Most metals react with strong acids. Gold is such an unreactive metal that it does not react with strong acids. This became known as “the acid test” because it stopped tricksters making false claims that something was gold. The phrase “the acid test” is used today to mean any process that will reveal fakes.

Metals and acid – experiment

Metals and acid – general equation Gold is an unreactive metal that does not react with acid. Other metals, such as magnesium and zinc, react with acid producing bubbles of gas. The “squeaky pop” test shows that this gas is hydrogen. When a metal reacts with acid, the products are a metal salt and hydrogen. What is the general equation for the reaction of a metal with acid? metal acid metal salt hydrogen How does the type of acid affect the type of salt produced?

Metals and hydrochloric acid – equations What is made when each metal reacts with hydrochloric acid? What is the balanced symbol equation for each reaction?  hydrochloric acid + magnesium magnesium chloride + hydrogen Mg + 2HCl  MgCl2 H2  hydrochloric acid + aluminium aluminium chloride + hydrogen 2Al + 6HCl  2AlCl3 3H2  hydrochloric acid + zinc zinc chloride + hydrogen Zn + 2HCl  ZnCl2 H2

Metals and sulfuric acid – equations What is made when each metal reacts with sulfuric acid? What is the balanced symbol equation for each reaction?  sulfuric acid + magnesium magnesium sulfate + hydrogen Mg + H2SO4  MgSO4 H2  sulfuric acid + aluminium aluminium sulfate + hydrogen 2Al + 3H2SO4  Al2(SO4)3 3H2  sulfuric acid + zinc zinc sulfate + hydrogen Zn + H2SO4  ZnSO4 H2

Metals and nitric acid – equations What is made when each metal reacts with nitric acid? What is the balanced symbol equation for each reaction?  nitric acid + magnesium magnesium nitrate + hydrogen Mg + 2HNO3  Mg(NO3)2 H2  nitric acid + aluminium aluminium nitrate + hydrogen 2Al + 6HNO3  2Al(NO3)3 3H2  nitric acid + zinc zinc nitrate + hydrogen Zn + 2HNO3  Zn(NO3)2 H2

Metals and acid – observations Greg investigated how reactive some metals are with hot and cold acid and made these observations. Metal Reaction with cold acid (HCl) Reaction with hot acid (HCl) magnesium Fizzed rapidly - aluminium Bubbled quickly copper No reaction iron Slow bubbling lead Occasional bubble calcium Really fast zinc Moderate bubbling Which of these metals is the most reactive with acid? Which of these metals is the least reactive with acid?

Metals and acid – order of reactivity Put the following metals in order of reactivity based on their reaction with acid, starting with the most reactive: aluminium, calcium, copper, iron, lead, magnesium, zinc. calcium magnesium aluminium zinc iron lead copper

Metals and acid – reactivity activity

Reactivity series and displacement

Comparing orders of reactivity When the orders of reactivity of metals with water, oxygen and air are compared, there is a pattern of results. with water potassium sodium lithium magnesium copper silver gold with oxygen magnesium iron copper with acid calcium magnesium aluminium zinc iron lead copper Combining the information from all the reactions of metals with water, oxygen and air gives an overall order of reactivity called the reactivity series.

increasing reactivity The reactivity series The reactivity series is the list of metals placed in order of their reactivity. One way to remember this order is to learn this silly sentence: potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold Please send Charlie’s monkeys and zebras in lead cages securely guarded! increasing reactivity

What is the order of metals?

Using the reactivity series The reactivity series can be used to make predictions about the reactions of metals. Predictions can be made about simple reactions of metals with oxygen, water and acids. Predictions can also be made about more complex reactions where one metal is competing with another. potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold increasing reactivity

Simple reactions – predictions Use the reactivity series to predict if a reaction will take place and how intense the reaction will be. Metal React with Prediction gold acid calcium water sodium oxygen silver zinc potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold no reaction fizzing burns vigorously very slow reaction burns moderately

When does displacement happen? The reactivity series can be used to predict if a metal will react with a metal compound (e.g. chloride, nitrate or sulfate). If the metal is more reactive than the metal in the compound, it competes with the less reactive metal.  + less reactive metal compound more reactive metal + less reactive metal more reactive metal compound The more reactive metal pushes out, or displaces, the less reactive metal from its compound. If the metal is less reactive than the metal in the compound, it will not compete and so there is no reaction. + no reaction  more reactive metal compound less reactive metal

Displacement reactions – examples The reactivity series can be used to predict if a metal will react with a metal compound. Will magnesium react with copper chloride?  copper chloride + magnesium copper + magnesium chloride Magnesium is a more reactive metal than copper, so magnesium displaces the copper from its compound. Will silver react with magnesium chloride?  magnesium chloride + silver no reaction Silver is a less reactive metal than magnesium, so silver does not displace the magnesium from its compound.

Displacement reactions – observation This photograph shows what happens when magnesium reacts with copper sulfate. Why does the blue colour of the coppers sulfate solution gradually disappear during this reaction? before after copper + magnesium sulfate  copper sulfate magnesium Magnesium is a more reactive metal than copper and so the magnesium displaces the copper from the copper sulfate solution. This is why the blue colour disappears.

Displacement of sulfates – predictions Use the reactivity series to predict if there is a reaction when these metals are added to different metal sulfate solutions. magnesium sulfate zinc sulfate iron copper sulfate magnesium copper metal sulfate solution metal              = displacement reaction = no reaction 

Displacement of sulfates – magnesium Does magnesium react with and displace these metal sulfates and if so what products are formed?  copper sulfate + magnesium magnesium sulfate + copper  Mg + CuSO4  MgSO4 Cu  zinc sulfate + magnesium magnesium sulfate + zinc  Mg + ZnSO4  MgSO4 Zn  iron sulfate + magnesium magnesium sulfate + iron  Mg + FeSO4  MgSO4 Fe

Displacement of sulfates – zinc Does zinc react with and displace these metal sulfates and if so what products are formed?   magnesium sulfate + zinc no reaction  iron sulfate + zinc zinc sulfate + iron  Zn + FeSO4  ZnSO4 Fe  copper sulfate + zinc zinc sulfate + copper  Zn + CuSO4  ZnSO4 Cu

Displacement of sulfates – iron Does iron react with and displace these metal sulfates and if so what products are formed?   magnesium sulfate + iron no reaction   zinc sulfate + iron no reaction  copper sulfate + iron iron sulfate + copper  Fe + CuSO4  FeSO4 Cu

Displacement of sulfates – copper Does copper react with and displace these metal sulfates and if so what products are formed?   magnesium sulfate + copper no reaction   zinc sulfate + copper no reaction   copper sulfate + copper no reaction

Displacement of oxides Displacement reactions can also occur between a metal and a metal compound that is a solid.  iron oxide + aluminium iron + aluminium oxide The more reactive aluminium wins the oxygen from the less reactive iron. The reaction gets so hot that the iron melts! This is the Thermit reaction and is used to weld railway lines.

Displacement of oxides – predictions Use the reactivity series to predict if there is a reaction when each mixture of a metal and a metal oxide is heated. zinc oxide iron copper oxide copper metal oxide metal        = displacement reaction = no reaction 

Displacement of oxides – zinc Does zinc react with and displace these metal oxides and if so what products are formed?  copper oxide + zinc zinc oxide + copper  Zn + CuO  ZnO Cu  iron oxide + zinc zinc oxide + iron  3Zn + 2Fe2O3  3ZnO 2Fe Zinc is the more reactive than copper and iron.

Displacement of oxides – iron Does iron react with and displace these metal oxides and if so what products are formed?   zinc oxide + iron no reaction  copper oxide + iron iron oxide + copper  2Fe + 3CuO  Fe2O3 3Cu Iron is less reactive than zinc but more reactive than copper.

Displacement of oxides – copper Does copper react with and displace these metal oxides and if so what products are formed?   zinc oxide + copper no reaction   iron oxide + copper no reaction Copper is less reactive than zinc and iron and will not displace either of these metals.

Displacement reactions – activity Use the reactivity series to predict if each mixture will react. Reactants Reaction? iron oxide magnesium potassium sodium calcium magnesium aluminium zinc iron lead copper silver gold  copper sulfate zinc  potassium hydrochloric acid   gold iron chloride  calcium sodium chloride calcium oxygen 

Displacement reactions – activity Use the reactivity series to predict if each mixture will react and complete the word equation.  aluminium oxide + magnesium magnesium oxide + aluminium  iron chloride + magnesium magnesium chloride + iron  zinc oxide + silver no reaction  gold nitrate + copper copper nitrate + gold

Contents Summary activities

reactive – A substance that reacts quickly or easily. Glossary displaced metal – The metal that is pushed out of a compound by a more reactive metal. displacement – A reaction in which a more reactive metal replaces a less reactive metal in a compound. reactive – A substance that reacts quickly or easily. reactivity – How quickly or easily a substance will react. reactivity series – The list of metals placed in order of their reactivity starting with the most reactive. tarnished – A metal that has become dull after reacting with water and oxygen in the air. Thermit reaction – The displacement reaction between aluminium and iron oxide that is used to weld railway lines. unreactive – A substance that reacts very slowly or does not react at all.

True or false?