The Activity of Metals
Name:
Purpose: To rank several metals in reactivity by performing single replacement
reactions.
Background: Some metals are more reactive than others. If a metal is
extremely reactive, it will react with a non-reactive substance such as water. For
example, sodium reacts with water in the following equation:
2Na + 2H2O  2NaOH + H2
Magnesium is not as reactive as sodium, and so it will not react with water. To
make magnesium react, we must combine it with a more reactive substance,
such as hydrochloric acid (a.k.a. HCl or hydrogen chloride):
Mg + 2HCl  MgCl2 + H2
You will be able to determine if a reaction occurs if bubbles (H2) are produced.
To rank the metals in order of reactivity, you will first test them all with H2O.
The most reactive metals will react with the water; the less reactive metals will
not. You will then test the less reactive group of metals with HCl. Those that
react have medium reactivity; those that don’t are the least reactive group.
All Metals
yes
Reacts with H2O?
no
Medium or Low
Reactivity
High Reactivity
yes
Medium Reactivity
Reacts with HCl?
no
Low Reactivity
Within each group, you must rank the metals further. To do so, you must
observe the vigorousness of the reactions; a highly reactive metal will produce a
lot of bubbles faster than a less reactive metal.
Part I
Procedure:
1. Observe the demonstration of sodium and potassium with water.
2. Obtain a well plate. Put small pieces of Mg, Ca, Sn, Cu, Al, and Zn into six
wells (your instructor will handle the Ca for you; do not touch it with your
fingers).
3. Add ten drops of distilled water into each well. Record your observations.
4. IF THE METAL REACTS, DO NOT TEST IT WITH ACID.
5. Add ten drops of HCl to the wells containing metals that did not react with
water. Record your observations.
6. Discard the unreacted metals in the garbage and pour the liquid down the
sink.
Part II
A more reactive metal will replace a less reactive metal in a compound. If a
more reactive metal is placed in a solution of an ionic compound of a less
reactive metal, the more reactive metal will replace the less reactive metal
(single replacement reaction), and the less reactive metal will precipitate out of
solution:
2K(s) + MgSO4(aq)  Mg(s) + K2SO4(aq)
In this section, you will rank Al, Cu, and Mg using this method. You will perform
the following six reactions; if the reaction occurs, you know the solid metal is
more reactive than the metal in the compound.
2Al(s) + 3MgSO4(aq)  3Mg(s) + 2Al2(SO4)3(aq)
2Al(s) + 3CuSO4(aq)  3Cu(s) + 2Al2(SO4)3(aq)
3Mg(s) + Al2(SO4)3(aq)  2Al(s) + 3MgSO4(aq)
Mg(s) + CuSO4(aq)  Cu(s) + MgSO4(aq)
Cu(s) + MgSO4(aq)  Mg(s) + CuSO4(aq)
3Cu(s) + Al2(SO4)3(aq)  2Al(s) + 3CuSO4(aq)
Procedure:
1. Obtain two pieces each of Al, Cu, and Mg.
2. Place each piece of Al into separate wells of a well plate. To one of the
wells add 20 drops of CuSO4 solution. To the other add 20 drops of
MgSO4 solution. Watch for signs of a chemical change (bubbles or
precipitate) for five minutes; record your observations.
3. Repeat step two using solid Cu and solutions of Al2(SO4)3 and MgSO4.
4. Repeat step two using solid Mg and solutions of Al2(SO4)3 and CuSO4.
5. Pour liquids down the sink and dispose of the metals in the garbage.
Write-Up
This will be a full lab report. It must be typed and double-spaced. It should
include:
Purpose
Part I
Procedure
Observations
Results – your activity series
Part II
Procedure
Observations
Results – your activity series
Conclusion –
-Do your results make sense based on your knowledge of periodic
trends?
-We have discussed that exceptions to the trends can occur. However, let
us assume that everything should work exactly as predicted from the
periodic table. (So exceptions to the rules are not a possibility). With this
in mind, what are 3 possible lab errors that could contribute to incorrect
results? (DON’T SAY “Human error”)
For the purpose and procedures, please download this lab sheet from my
website and copy directly into your write-up.