Use an activity series to determine whether or not the following reactants will react Mg +snno3

Learning Objectives

Use the activity series to predict if a reaction will occur.

We see two metals below that can be exposed to water. The picture on the left is of sodium, which gives a violent reaction when it comes in contact with water. The picture on the right is of silver, a metal so unreactive with water that it can be made into drinking vessels.

Single-replacement reactions only occur when the element that is doing the replacing is more reactive than the element that is being replaced. Therefore, it is useful to have a list of elements in order of their relative reactivities. The activity series is a list of elements in decreasing order of their reactivity. Since metals replace other metals, while nonmetals replace other nonmetals, they each have a separate activity series. The table below is an activity series of most common metals and of the halogens.

Table \(\PageIndex{1}\): Activity Series of Metals in Aqueous Solutions

Most Active (Easily Oxidized—Readily Lose Electrons)
lithium	Li	These metals displace hydrogen from water Ca(s) + 2H2O(l)→ Ca(OH)2 + H2 (g). These elements are very reactive and react readily to form compounds.
potassium	K
barium	Ba
calcium	Ca
sodium	Na
	These metals displace hydrogen from acids Zn(s) + HCl(aq)→ ZnCl2 + H2(g)
magnesium	Mg
aluminum	Al
zinc	Zn
chromium	Cr
iron	Fe
cadmium	Cd
nickel	Ni
tin	Sn
lead	Pb

hydrogen	H

copper	Cu	These metals do not displace hydrogen from acids or water. These elements are more stable, and form compounds less readily than do those higher in the table.
silver	Ag
mercury	Hg
platinum	Pt
gold	Au
Least Active

For a single-replacement reaction, a given element is capable of replacing an element that is below it in the activity series. This can be used to predict if a reaction will occur. Suppose that small pieces of the metal nickel were placed into two separate aqueous solutions: one of iron (III) nitrate and one of lead (II) nitrate. Looking at the activity series, we see that nickel is below iron, but above lead. Therefore, the nickel metal will be capable of replacing the lead in a reaction, but will not be capable of replacing iron.

\[\ce{Ni} \left( s \right) + \ce{Pb(NO_3)_2} \left( aq \right) \rightarrow \ce{Ni(NO_3)_2} \left( aq \right) + \ce{Pb} \left( s \right)\]

\[\ce{Ni} \left( s \right) + \ce{Fe(NO_3)_3} \left( aq \right) \rightarrow \text{NR (no reaction)}\]

In the descriptions that accompany the activity series of metals, a given metal is also capable of undergoing the reactions described below that section. For example, lithium will react with cold water, replacing hydrogen. It will also react with steam and with acids, since that requires a lower degree of reactivity.

Steps for Problem Solving

Example \(\PageIndex{1}\)

Use the activity series to predict if the reaction below will occur. If not, write \(\text{NR}\). If the reaction does occur, write the products of the reaction and balance the equation.

\(\ce{Al} \left( s \right) + \ce{Zn(NO_3)_2} \left( aq \right) \rightarrow\)

Example \(\PageIndex{2}\)

Use the activity series to predict if the reaction below will occur. If not, write \(\text{NR}\). If the reaction does occur, write the products of the reaction and balance the equation.

\(\ce{Ag} \left( s \right) + \ce{HCl} \left( aq \right) \rightarrow\)

Plan the problem.

Compare the placements of aluminum (the element doing the replacing) and zinc (the element being replaced) on the activity series.

Compare the placements of silver (the element doing the replacing) and hydrogen (the element being replaced) on the activity series.

Solve.

Since aluminum is above zinc, it is capable of replacing it and a reaction will occur. The products of the reaction will be aqueous aluminum nitrate and solid zinc. Take care to write the correct formulas for the products before balancing the equation. Aluminum adopts a \(+3\) charge in an ionic compound, so the formula for aluminum nitrate is \(\ce{Al(NO_3)_3}\). The balanced equation is:

\[2 \ce{Al} \left( s \right) + 3 \ce{Zn(NO_3)_2} \left( aq \right) \rightarrow 2 \ce{Al(NO_3)_3} \left( aq \right) + 3 \ce{Zn} \left( s \right)\]

Since silver is below hydrogen, it is not capable of replacing hydrogen in a reaction with an acid.

\[\ce{Ag} \left( s \right) + \ce{HCl} \left( aq \right) \rightarrow \text{NR}\]

Exercise \(\PageIndex{1}\)

Use the activity series to predict if the following reactions will occur. If not, write \(\text{NR}\). If the reaction does occur, write the products of the reaction and balance the equation.

a. Would it be possible to store a silver spoon in a zinc nitrate solution? That is, will the following reaction occur?

\Ag_{(s)} + Zn(NO_3)_{2 (aq)} →

b. Would it be possible to store a silver nitrate solution in a copper container? That is, will the following reaction occur?

\[Cu_{(s)} + AgNO_{3 (aq)} →

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In a single replacement reaction, a metal and a metal compound may react so that the metal will replace the metal in the compound, producing the replaced metal and a new compound with the original metal.

#"A + BC"##rarr##"B + AC"#,

where #"A"# and #"B"# are metals, and #"C"# is a negative ion.

In order to determine whether this will actually happen, you consult an activity series of metals. An activity series of metals lists metals in descending order of reactivity. This means that a metal can only replace a metal below it in the series.

Example 1: Will the following single replacement reaction occur?

#"Cu(s) + Zn(NO"_3)_2("aq")"##rarr##"Zn(s) + Cu(NO"_3)_2"#

If we look at the activity series above, we see that copper is below zinc, so it cannot replace the zinc in the zinc nitrate compound. So this reaction will not occur. We would write it as:

#"Cu(s) + Zn(NO"_3)_2("aq")"##rarr##"no reaction"#

Example 2: Will the following single replacement reaction occur?

#"2Al(s) + 3CuSO"_4("aq")"##rarr##"3Cu(s) + Al"_2("SO"_4)_3"#

If we look at the activity series, we see that aluminum is above copper, so this reaction will occur, and the aluminum will replace the copper to form aluminum sulfate.

The video shows an experiment to determine the placement of three different metals (Cu, Zn and Mg) on the activity series.

Video from: Noel Pauller"