Chemistry 30 Electrochemistry - Activity Series
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Chemistry 30
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Redox Reactions & Electrochemistry
2.5 The Activity Series
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As we mentioned earlier (Section 2-3), elements differ in their reactivity. Some elements are so reactive
that they do not occur naturally in their elemental form; rather they only exist in nature as part of a
compound. Other elements are essentially completely unreactive and are chemically inert (the Noble
gases).
An activity series is often useful is helping to predict whether certain reactions will occur. An activity
series list metals and various other elements in order of their reactivity, with the most reactive elements at
the top and the least reactive of the series at the bottom. For any two metals, the metal listed higher in the
table is the most readily oxidized.
Activity Series of Metals in Aqueous Solutions
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most active (easily oxidized – readily lose electrons))
lithium
potassium
barium
calcium
sodium
Li
K
These metals displace hydrogen from water
Ba
Ca(s) + 2H2O(l)→ Ca(OH)2 + H2 (g)
Ca
These elements are very reactive and
react readily to form compounds
Na
Mg
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Chemistry 30 Electrochemistry - Activity Series
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magnesium
aluminum
zinc
chromium
A
Zn
Cr
These metals displace hydrogen from acids
iron
cadmium
nickel
tin
lead
hydrogen
copper
silver
mercury
platinum
gold
Fe
Zn(s) + HCl(aq)→ ZnCl2 + H2(g)
Cd
Ni
Sn
Pb
H
Cu
Ag
These metals do not displace hydrogen from acids or
water
Hg
Pt
These elements are more stable, and form compounds less
readily than do those higher in the table.
Au
least active
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Chemistry 30 Electrochemistry - Activity Series
4/22/14 10:49 AM
Some examples of how reactions can be predicted using an activity series:
Any metal on the list can be oxidized by the ions of elements below it in the chart. For example
copper is above silver in the chart. Thus, copper metal will be oxidized by silver ions as in the
following example:
Cu(s) + 2 AgNO3 (aq) → Cu(NO3)2 (aq) + 2 Ag(s)
Would it be possible to store a silver spoon in a zinc nitrate solution? That is, will the following
reaction occur:
Ag(s) + Zn(NO3)2 (aq) → 2 AgNO3 (aq)+ (aq) + Zn (s)
Since silver is below zinc on the chart, silver metal will not be oxidized by zinc. Therefore
it would be safe to store the silver spoon in the zinc solution; the silver spoon will not
undergo oxidation and corrode.
Would it be possible to store a silver nitrate solution in a copper container? That is, will the
following reaction occur:
Cu(s) + 2 AgNO3 (aq) → Cu(NO3)2 (aq) + 2 Ag(s)
We do not want this reaction to occur, since the copper container would corrode.
From the table we find that Cu is a more easily oxidized than is Ag. In other words, copper
will undergo oxidation and the reaction will occur. Therefore, it is not recommended to
store AgNO3 in a copper container.
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