Metal Activity Series - Background

Metal Activity Series



Activity Series

The relative reactivity of metals can be used to organize them into an activity series. Once organized, an activity series helps us to predict if a reaction will occur when a piece of elemental metal is placed in water, an acid solution, or a solution containing the ion of another metal.

Activity series are generally listed in order of decreasing reactivity. This means that in a metal activity series we would find the most reactive metals at the top. Only a few of the most reactive metals are able to displace hydrogen from water while a larger number will displace H+ from an acid. The least reactive metals are not able to displace hydrogen from either of these and are therefore found at the bottom of the series.

Organizing the metals in this fashion also allows us to predict how the metals will react with each other. In a solution or compound, an elemental metal will displace any metal lower than it on the activity series.


An Example Activity Series


From the activity series above, we can predict that aluminum will not displace H from water. However, it will displace H+ from an acid by the following single displacement reaction.

2 Al(s) + 6 HCl(aq) 3 H2(g) + 2 AlCl3(aq) (molecular equation)
2 Al(s) + 6 H+(aq) 3 H2(g) + 2 Al+3(aq) (net ionic equation)

We could also predict that aluminum will displace mercury from solution by the following reaction.

2 Al(s) + 3 Hg(NO3)2(aq) 3 Hg(l) + 2 Al(NO3)3(aq) (molecular equation)
2 Al(s) + 3 Hg+2(aq) 3 Hg(l) + 2 Al+3(aq) (net ionic equation)


Continue on and read about how we set up an activity series.


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