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MODULE 2
5
WORKSHEET
REACTIONS OF METALS
Syllabus reference 8.3.2
1
All common metals react with oxygen to form oxides, while some metals including silver, platinum
and gold do not react with oxygen.
a Complete the following table.
POSITION IN
PERIODIC TABLE
METAL
b
REACTION
WITH OXYGEN
EQUATION
Sodium
Group 1
Reacts readily at room
temperature
Magnesium
Group 2
Reacts slowly at room 2Mg(s)  O2(g) → 2MgO(s)
temperature but rapidly
2Zn(s)  O2(g) → 2ZnO(s)
if heated
Zinc
Transition metal
Copper
Transition metal
Reacts slowly when
heated
4Na(s)  O2(g) → 2Na2O(s)
2Cu(s)  O2(g) → 2CuO(s)
Using the above information rank these metals from most active to least active.
Na, Mg, Zn, Cu
c
Where in the periodic table is the most reactive of these metals located?
Groups 1 and 2 (left hand side of the Periodic Table)
2
Some metals react with oxygen until all the metal has reacted, while other metals react to form an
oxide coating that protects the metal from further reaction.
a Name one metal that undergoes complete reaction (corrosion).
Iron
b
Name two metals that form an oxide coating that makes it resistant to further reaction.
Aluminium, zinc
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CONQUERINGCHEMISTRY PRELIM
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3
Some metals react with water or steam. The more active metals form hydroxides with water while
the less active metals form hydroxides with steam.
a Complete the following table.
METAL
Potassium
Sodium
Aluminium
Zinc
Lead
Copper
b
POSITION IN
PERIODIC TABLE
Group 1
Group 1
REACTION
WITH WATER
Reacts with water at
room temperature
Transition metal
2K(s)  2H2O(l) → 2KOH(aq)  H2(g)
2Na(s)  2H2O(l) → 2NaOH(aq)  H2(g)
2Al(s)  3H2O(l) → Al2O3(s)  3H2(g)
Group 3
Transition metal
EQUATION
Reacts with steam
Zn(s)  H2O(l) → ZnO(s)  H2(g)
No reaction
Does not react
No reaction
Transition metal
On the basis of the above information rank these metals from most active to least active.
K, Na, Al, Zn, Pb, Cu
c
Where in the Periodic Table are the most reactive metals located?
Group 1 and 2 (left hand side of the Periodic Table)
d
Where in the Periodic Table are the least reactive metals located?
Right side of the Periodic Table before the non-metals
4
Most metals react with dilute hydrochloric acid and sulfuric acid to form hydrogen gas. The speed
at which the reactions occur varies depending on the reactivity of the metal.
a Complete the following table.
METAL
Sodium
Calcium
Zinc
Iron
Tin
Lead
b
POSITION IN
PERIODIC TABLE
Group 1
Group 2
Transition metal
Transition metal
Transition metal
Transition metal
REACTION
WITH ACID
EQUATION
Reacts vigorously at
room temperature
Reacts quickly at room
temperature
Reacts slowly at room
temperature
2Na(s)  2HCl(aq) → 2NaCl(aq)  H2(g)
Ca(s)  2HCl(aq) → CaCl2(aq)  H2(g)
Zn(s)  2HCl(aq) → ZnCl2(aq)  H2(g)
Fe(s)  2HCl(aq) → FeCl2(aq)  H2(g)
Sn(s)  2HCl(aq) → SnCl2(aq)  H2(g)
Pb(s)  2HCl(aq) → PbCl2(aq)  H2(g)
On the basis of the above information rank these metals from most active to least active.
Na, Ca, Zn, Fe, Sn, Pb
c
Where in the Periodic Table are the most reactive metals located?
Group 1 and 2 (left hand side of the Periodic Table)
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CONQUERINGCHEMISTRY PRELIM
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d
Where in the Periodic Table are the least reactive metals located?
Right side of the Periodic Table before the non-metals
5
Use the information in questions 2, 4 and 5 to identify on the periodic table below where the most
active and least active metals are located.
Most active
Least active
Al
Na Mg
K
Ca
Fe
Cu
Zn
Ag
Sn
Au
Pb
Make a summary statement about how activity of metals changes from left to right across the
table (ignoring transition metals).
Activity of metals decreases from left to right
6
The following experiment was performed to determine the relative reactivities of several metals.
Pieces of each metal were added in turn to 5 mL water and to 5 mL of 0.5 mol/L hydrochloric
acid solution in test tubes. Each test tube was carefully observed to see whether any bubbles of
colourless gas formed. Results are tabulated below. A tick means that a gas was formed and a
cross means no gas appeared.
a
Ca
Cu
Fe
Li
Ag
Zn
With water
✓
X
X
✓
X
X
With HCl
✓
X
✓
✓
X
✓
What is the colourless gas being formed?
Hydrogen gas
b
Use the results in the table to arrange the metals into three groups—highly reactive,
moderately reactive, not reactive.
Highly reactive – Ca, Li
Moderately reactive – Fe, Zn
Not reactive – Cu, Ag
c
If there is more than one metal in each of the categories moderately reactive, not reactive,
suggest an investigation you could do to distinguish between the reactivities of these metals.
Place a piece of one metal in a solution containing the metal ion of the other and see which one
reacts. The reaction where the metal comes out of the solution means that that metal is the less
reactive of the two because a more reactive metal displaces a less reactive metal from solution.
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CONQUERINGCHEMISTRY PRELIM
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7
a
What is the difference between oxidation and reduction?
Oxidation is loss of electrons and reduction is gain of electrons.
b
Why do oxidation and reduction reactions always occur together?
Oxidation and reduction reactions involve a transfer of electrons so there must always be a
species which loses electrons and a species which gains electrons.
8
Consider the following reaction.
2Mg(s) + O2(g) → 2MgO(s)
a
Identify the species being oxidised.
Mg
b
Identify the species being reduced.
O2
c
Write the two half reactions.
Mg → Mg2  2e
O2  4e → 2O2
9
Rewrite the following as two half reactions.
a 2Ca(s) + O2(g) → 2CaO(s)
Ca → Ca2  2e
O2  4e → 2O2
b
2Al(s) + 6H+(aq) → 2Al3+(aq) + 3H2(g)
Al → Al3  3e
2H  2e → H2
Reproduced by permission
10 Consider the cartoon below. Explain the relevance of the caption at the bottom.
Mg is more reactive than Cu so when Mg is placed in a solution containing Cu2 ions it will react
to produce Mg2 ions and the copper will deposit out of solution. The Mg solid will disappear
into solution.
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CONQUERINGCHEMISTRY PRELIM
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