1. Activity series
Experiment # 15

2. What we are doing today:
We are going to test reactions of metals with acids
We are going to test single replacement reactions.
We are going to determine a relative activity series BASED ON OUR EXPERIMENTAL DATA

3. What does reactivity mean?
9F Reactivity in chemistry
What does reactivity mean?
Elements that are reactive readily take part in reactions with other chemicals.
But an element might react very quickly with one chemical and hardly at all with another. So is it reactive or not?
To compare the reactivity of different elements, we might see how easily they react with oxygen.
Some metals corrode in minutes out on the bench.
Others take longer to corrode, unless you heat them.

4. We can list metals in order of how quickly they react with oxygen.
9F The Gold Cup again?
We can list metals in order of how quickly they react with oxygen.
speed of reaction with oxygen
least reactive
most reactive
This ranking of metals according to reactivity is called the reactivity series.

5. What if we react different metals with acid?
9F Reaction of metals with acid
What if we react different metals with acid?
iron – the metal reacts slowly, producing a few bubbles
copper – no bubbles, no reaction with acid
lead – the metal reacts very slowly, producing very few bubbles
magnesium – the metal reacts quickly with the acid, producing lots of bubbles
sodium – the metal bursts into flames, a very strong reaction

6. reactivity series with
9F What about water?
We can also rank metals by their reaction with water.
Compare with the reactivity series for oxygen and acid.
reactivity series with
oxygen
acid
water
potassium
sodium magnesium zinc iron lead copper gold
potassium sodium magnesium zinc iron lead copper gold
The reactivity series is very useful. How can we learn it?

7. metal symbol useful mnemonic?
9F Remembering the series
metal
symbol
useful mnemonic?
potassium sodium magnesium aluminium zinc iron lead hydrogen copper gold
K Na Mg Al Zn Fe Pb H Cu Au
Kangaroos Naturally Muck About in Zoos For Purple Hippos Chasing Aardvarks
Come on, you can think of a better mnemonic!

8. The reactivity series allows you to make predictions.
9F Using the series
The reactivity series allows you to make predictions.
Choose from the box below. What will happen when you mix...
...a metal
…and an acid?
potassium
hydrochloric acid
magnesium
iron
copper
gold
very violent reaction
fast reaction
gas bubbles form slowly
nothing happens
nothing happens
nothing happens gas bubbles form slowly
fast reaction nothing happens
very violent reaction

9. Magnesium is more reactive than copper.
9F Feeling a bit displaced?
A single replacement reaction happens when one metal replaces another one in a compound.
Magnesium is more reactive than copper.
Magnesium displaces copper from copper sulphate solution.
magnesium + copper sulphate magnesium sulphate + ?

10. Write a word equation for this reaction.
9F A model for displacement reactions
This model will help explain displacement reactions.
Think of reactivity as aggression!
Write a word equation for this reaction.

11. Part A To six test tubes add approximately 0.5 ml of HCl
Add a small piece Ca metal to the test tube
Record all changes
Repeat for all five metals
Write complete and ionic equations for each metal

12. Part B
To one test tube add approximately 0.5 ml of a polyatomic ionic compound Ca(NO3)2
Repeat for each of the other six polyatomic ionic compounds
Add a small piece Ca metal to each test tube
Record all changes
Repeat for all five metals
Write complete and ionic equations for each metal

13. Part B
Dispose of the waste and Repeat all procedures for each of the other five metals
Write complete and net ionic equations for each metal

14. Part C
Based on your experimental data determine a relative activity series of the metals in question Ca Cu Fe Mg Sn Zn Al

15. Types of chemical equations
Equations can be divided into 3 types
1) Molecular, 2) Ionic, 3) Net ionic
Here is a typical molecular equation:
Cd(NO3)2(aq) + Na2S(aq)  CdS(s) + 2NaNO3(aq)

16. We can write this as an ionic equation
(all compounds that are (aq) are written as ions):
Cd2+(aq) + 2NO3–(aq) + 2Na+(aq) + S2–(aq)  CdS(s) + 2Na+(aq) + 2NO3–(aq)

17. Net Ionic equations
Cd2+(aq) + 2NO3–(aq) + 2Na+(aq) + S2–(aq)  CdS(s) + 2Na+(aq) + 2NO3–(aq)
To get the NET ionic equation we cancel out all terms that appear on both sides:
Net: Cd2+(aq) + S2–(aq)  CdS(s)

18. Equations must be balanced
There are two conditions for molecular, ionic, and net ionic equations
Materials balance
Both sides of an equation should have the same number of each type of atom
Electrical balance
Both sides of a reaction should have the same net charge

19. Due next week
Pg 167 and 168
Need to show all work for full credit!!