Chemistry Reference
In-Depth Information
With air/oxygen
Many metals react directly with oxygen to form
oxides. For example, magnesium burns brightly in
oxygen to form the white powder magnesium oxide.
magnesium
2Mg(
s
)
+
+
oxygen
O
2
(
g
)
magnesium oxide
2MgO(
s
)
→
→
With water/steam
Reactive metals such as potassium, sodium and
calcium react with cold water to produce the metal
hydroxide and hydrogen gas. For example, the
reaction of sodium with water produces sodium
hydroxide and hydrogen.
sodium
+
water
sodium
hydroxide
2NaOH(
aq
)
+
hydrogen
H
2
(
g
)
→
●
●
→
2Na(
s
)
+
2H
2
O(
l
)
+
a
This wood-burning stove is made of iron.
The moderately reactive metals, magnesium, zinc
and iron, react slowly with water. They will, however,
react more rapidly with steam (Figure 10.3). In their
reaction with steam, the metal oxide and hydrogen
are formed. For example, magnesium produces
magnesium oxide and hydrogen gas.
magnesium
Mg(
s
)
+
steam
H
2
O(
g
)
magnesium
oxide
MgO(
s
)
+
hydrogen
H
2
(
g
)
→
●
●
→
+
+
rocksil wool
soaked in
water
b
Copper pots and pans.
Figure 10.4
metal sample
(magnesium,
zinc, iron)
hydrogen
rubber
bung
water
heat
heat
Figure 10.3
Apparatus used to investigate how metals such as
magnesium react with steam.
Figure 10.5
Planes are made of an alloy which contains magnesium and
aluminium.
Generally, it is the unreactive metals that we find
the most uses for; for example, the metals iron
and copper can be found in many everyday objects
(Figure 10.4). However, magnesium is one of the
metals used in the construction of the Airbus A380
(Figure 10.5).
Both sodium and potassium are so reactive that they
have to be stored under oil to prevent them from
coming into contact with water or air. However,
because they have low melting points and are good
conductors of heat, they are used as coolants for
nuclear reactors.
