CHEMICAL REACTIONS 8.4 - Types of Reactions
CHEMICAL REACTIONS
8.4 - Types of Reactions
Single-Replacement Reactions
of Metals
Different metals have different reactivity. From unit 4 we learned that the
alkali
metals are most reactive metals. Not all metals are reactive. Metals such
as platinum and gold are not very reactive. Based on experimental investigations,
a tabulated list of metals summarizing the order of reactivity of metal is available
for reference. This list is known as the activity
series. For your convenience, the activity series is available for
access in the Chemist's tools 
.
Click on the 
icon . Your job is to learn how to use this list to make predictions of single-replacement
reactions involving metals. Do NOT memorize the activity series. In examination
situation, the activity series will be available for you to use.
A reactive metal in the activity series will displace the ion of any metal lower on the list.
When a piece of copper wire, Cu (s), is submerged in a solution of silver nitrate, AgNO3, a reaction occurs. Shiny needlelike crystals of silver form on the copper wire.
|
Cu (s) + 2 AgNO3
(aq)
 Cu(NO3)2
(aq) + 2 Ag (s) |
The above reaction fits the form
A + BC
AC
+ B
where A = Cu; B
= Ag+; C
= NO3-.
Click here
for a detailed look at this equation.
View the activity
series
and you will find that Cu is higher on the activity
series than Ag. The above single-replacement reaction occurs because Cu is
higher on the activity series than Ag. Therefore, Cu is capable of displacing
the Ag+ , which occurs lower of the activity series.
Single-Replacement Reactions of Nonmetals
As with metals, the reactivity of nonmetals are not the same. Some nonmetals are more reactive than others. In particular, we will concentrate on the halogens.
More reactive halogens react with compounds containing ions of less active halogens.
The order of reactivity for halogens, with the most reactive halogen listed first, is:
Bromine is prepared by reacting chlorine gas, Cl2, with aqueous sodium bromide, NaBr.
|
Cl2 (g) + 2 NaBr
(aq)
2 NaCl (aq)
+ Br2 (aq) |
The above reaction fits the form
A + BC
AC
+ B
where A = Cl2;
B = Na+; C
= Br-.
Click here
for a detailed look at this equation.
Cl2 replaces the bromide ion, Br- in NaBr because Cl2 is more reactive than Br-.
Section
9.8
Single-Replacement
Reactions
..p227
