1. Patterns of Reactivity
Unit 9F
Patterns of Reactivity

2. Learning outcome
Explain the process of tarnishing and state the scientific name for it
Carry out an experiment to place certain metals in order of reactivity

3. Tarnishing
What is tarnishing?

4. Look at the pictures below
In all of these images the metal has reacted.
What have they reacted with?

5. Most metals react with oxygen (tarnish) – but they may do so in very different ways. Some react faster than others and some may not react at all.
The reaction of a metal with oxygen is scientifically called
CORROSION.
All metals corrode but the corrosion of iron (and it’s alloys) has a special name – RUSTING.
In the laboratory this process can be speeded up by adding heat – i.e. burning.

6. Using corrosion to determine reactivity
We will now carry out an experiment to determine the reactivity of 3 metals.
What we will need:
Iron filings
Copper turnings
Magnesium strips
Bunsen burner
Tongs
Crucible
Tripod stand

7. Using corrosion to determine reactivity
What we will do:
Light the Bunsen burner
Using the tongs hold a piece of magnesium in the hot part of the flame.
Observe
Now put some iron turnings in to the crucible
Roast on a tripod stand
Repeat with the copper turnings

8. Reaction with oxygen - observations
Copy the table below and add your observations
Magnesium
The ribbon burned with a dazzling white flame giving grey-white smoke and ash.
Copper
The copper turnings went through reds and oranges and then slowly got a permanent coating of black.
Iron
The iron filings glowed red and sparkled leaving a brown-black looking solid.
They are all forming metal oxides.

9. Activity
Look at your observations and put these three metals in order of reactivity with oxygen - magnesium, copper, iron. 2. 3.
magnesium
iron
copper

10. Reaction with oxygen - equations
The equations are: 
oxygen +
magnesium
magnesium oxide
2Mg + O2 
2MgO 
oxygen +
copper
copper oxide
2Cu + O2 
2CuO 
oxygen +
iron
iron oxide
4Fe +
3O2 
2Fe2O3

11. Learning outcome
Describe the reactions of metals in water and create a reactivity series

12. Observing reactions with water
Some metals (like lead and copper) react only slowly with water. The word plumbing comes from plumbum (Latin for lead) because the ancient Romans used lead for their water pipes.
However, even lead does slowly dissolve and it is very poisonous. Because of this plumbers don’t use lead any more. (Should we re-name them coppers!)
Modern pipes – not lead but copper or plastic

13. Iron Copper Silver Gold Reaction with water
No rapid reaction but gradual conversion of the iron to rust
Copper
No reaction
Silver
No reaction
Gold
No reaction
This is, of course, relevant to the use of copper for plumbing and of silver and of gold for jewellery.

14. Reaction with water - observations
Calcium
Bubbles of hydrogen gas are given off quite quickly. The neutral water becomes alkaline.
Sodium
The sodium melts and skims over the surface producing a stream of small bubbles. Sometimes a yellow-orange flame appeared.
Potassium
Potassium immediately produced a lilac flame as it skimmed around making a fizzing noise.
All the metals are reacting to form metal hydroxides and hydrogen gas.

15. Other metals reaction with water
Watch the demonstration with the alkali and alkali earth metals
Why are alkali metals stored under oil?

16. Iron, sodium, potassium, silver, copper, calcium, gold 1. 2. 3. 4. 5
Activity
Put the following metals in order in terms of their reaction with water.
Iron, sodium, potassium, silver, copper, calcium, gold 1. 2. 3. 4. 5
potassium
sodium
calcium
iron
Copper, silver, gold

17. Reaction with water – equations
Equations for these reactions are: 
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

18. Learning outcome
Describe the reactions of metals in acid and create a reactivity series

19. Observing reactions with acid
The very first chemists were called alchemists. They spent much of their time trying to find methods of changing cheap metals into gold. Some were very good at making metals look gold.
But gold is so un-reactive that it wont dissolve even in really strong acids. Other metals do.
This became known as “the acid test” because it stopped tricksters making false claims that something was gold.
We still use the phrase “the acid test” to mean something that will show up fakes.
Most metals dissolve in strong acid – but gold doesn’t

20. Experiment What you need… 4 test tubes Test tube stand 0.1M HCl
Safety glasses
Pieces of
Copper
Magnesium
Lead
iron
What to do…..
Add a small amount of each metal to the bottom of a test tube
Half fill the test tube with acid
Observe the reaction

21. Acids and metals

22. Cold Acid (HCl) Hot Acid (HCl)
Reaction with acid
Metal
Cold Acid (HCl)
Hot Acid (HCl)
Magnesium
Fizzed rapidly -
Aluminium
Bubbled quickly
Copper
No reaction
Iron
Slow bubbling
Lead
Occasional bubble
Calcium
Really fast
Zinc
Moderate Bubbling

23. Match up the metals listed with the correct photo.
Activity
Match up the metals listed with the correct photo.
Copper, magnesium, iron, zinc
copper
Magnesium
iron
zinc
All the reactions involve the formation of a salt and hydrogen gas.

24. Reaction with acid - equations
Here are equations for some of the reactions 
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

25. Reaction with acid - equations
Here are equations for some of the reactions 
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

26. Reaction with acid – more equations
We get similar equations with sulphuric acid 
sulphuric acid +
magnesium
magnesium sulphate +
hydrogen Mg +
H2SO4 
MgSO4 H2 
sulphuric acid +
aluminium
aluminium sulphate +
hydrogen
2Al +
3H2SO4 
Al2(SO4)3
3H2 
sulphuric acid +
zinc
zinc sulphate +
hydrogen Zn +
H2SO4 
ZnSO4 H2

27. Reaction with acid – more equations
And with nitric acid… 
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

28. Learning outcome
Predict and create a reactivity series of metals using previous evidence
Explain displacement

29. 1 5 2 6 3 7 4 Activity calcium iron magnesium lead aluminium copper
Based on the reactions with acid, put the metals magnesium, aluminium, copper, iron, lead, calcium, zinc in order of reactivity (most reactive first). 1 5 2 6 3 7 4
calcium
iron
magnesium
lead
aluminium
copper
zinc

30. The Activity Series
We can combine all the information from the reactions with air, water and acid to get an overall activity series.
With Oxygen
magnesium
iron
oxygen
With water
potassium
sodium
lithium
With acid
calcium
magnesium
aluminium
zinc
Iron
Lead
copper
More complete studies give us the activity series shown on the next slide.

31. Increasing reactivity
The Reactivity Series
Increasing reactivity
Please
Send
Charlies
Monkeys
And
Zebras In
Lead
Cages
Securely
Guarded!
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Lead
Copper
Silver
Gold
One way of helping to remember this order is to learn the silly sentence:
Make your own mnemonic to help you learn the Reactivity series!!

32. The Activity Series - uses
We can use the activity series to make predictions about reactions we have not yet been able to try out.
This will apply both to simple reactions of the metals with oxygen, water and air.
It will also apply to more complex reactions where one metal is competing with another.

33. Learning outcome
Use the reactivity series to predict displacement reactions

34. Displaced metals
Displaced persons is an old-fashioned word for refugees: people who have lost their homes and possessions - often as a result of wars.
In chemistry we sometimes have displaced metals. These are metals that have lost a competition.
To start with such metals are bonded to a non-metal as part of a compound.
Along comes a more reactive metal and takes the non-metal away.

35. +

36. Can you predict what will happen?
Activity
Can you predict what will happen?
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

37. Activity Series – displacement reactions
We get situations where two metals are competing to be combined with a non-metal or non-metal group like nitrate or sulfate.
In such cases the more active metal wins the competition. E.g. 
copper chloride +
magnesium
magnesium chloride +
copper
The more reactive magnesium displaces the less reactive copper to “win” the chloride.
What will happen in this reaction? 
magnesium chloride +
silver
No reaction

38. Displacement Reactions - predictions
We can predict what will happen if we add metals to solutions of various metal sulphates in the table.
For example, 
copper sulphate +
magnesium
magnesium sulphate +
copper
Metal/ Solution
MgSO4
ZnSO4
FeSO4
CuSO4
Magnesium
Zinc
Iron
Copper            
 = reacts
 = no reaction

39. The solutions are added to a dip tile .
Activity
The solutions are added to a dip tile .
Pieces of metal are added to each dip.
Copper sulphate
Iron sulphate
Zinc sulphate
Magnesium sulphate
Reaction either does or does not take place.
Can you predict the outcomes? Cu Cu Mg Mg Mg Mg Mg Mg Zn Zn Zn Zn Cu Cu Zn Zn Fe Fe Fe Fe Fe Fe Cu Cu

40. Displacement Reactions - photos
Same reactions can, of course be carried out on a larger scale
Reaction between copper sulphate and magnesium.
Why does the blue copper sulphate colour gradually disappear?
The copper in the copper sulphate is turning into red copper metal.

41. Magnesium  copper sulphate + magnesium magnesium sulphate + copper Mg
CuSO4 
MgSO4 Cu 
zinc sulphate +
magnesium
magnesium sulphate +
zinc Mg +
ZnSO4 
MgSO4 Zn 
iron sulphate +
magnesium
magnesium sulphate +
iron Mg +
FeSO4 
MgSO4 Fe

42. Zinc  magnesium sulphate + Zinc No reaction Zn + MgSO4  - 
iron sulphate +
Zinc
zinc sulphate +
iron Zn +
FeSO4 
ZnSO4 Fe 
copper sulphate +
Zinc
zinc sulphate +
copper Zn +
CuSO4 
ZnSO4 Cu

43. Iron  magnesium sulphate + iron No reaction Fe + MgSO4  - 
zinc sulphate +
iron
No reaction Fe +
FeSO4  - 
copper sulphate +
iron
iron sulphate +
copper Fe +
CuSO4 
FeSO4 Cu

44. Copper  magnesium sulphate + copper No reaction Cu + MgSO4  - 
zinc sulphate +
copper
No reaction Cu +
FeSO4  - 
copper sulphate +
copper
No reaction Cu +
CuSO4  -

45. Copy the table below Solution Metal Iron Magnesium Copper Sulphate
Iron Sulphate
Magnesium Sulphate
Zinc Sulphate
Iron
Magnesium

46. Learning Outcome Explain how less reactive metals are extracted
Describe the process used to extract more reactive metals