Chemistry Reference
In-Depth Information
Al
3
Cl
(b) The
AlCl
3
is composed of
ions and
ions. The formula
Cl
Al
3
indicates that there are three times as many
ions as
ions.
Thus,
a
1 mol Al
3
1 mol AlCl
3
Moles
of salt
Moles
of ions
Formula
0.220 mol Al
3
0.220 mol AlCl
3
b
3 mol Cl
1 mol AlCl
3
0.660 mol Cl
0.220 mol AlCl
3
a
b
The concentrations of the ions are
0.220 mol Al
3
0.500 L
0.440 M Al
3
0.660 mol Cl
0.500 L
1.32 M Cl
Practice Problem 11.14
(a)
Calculate the molarity of if 0.150 mol of that compound is
dissolved in enough water to make 2.70 L of solution.
Al
2
(SO
4
)
3
(b)
Calculate the concentration of each ion in that solution.
When two different compounds containing an ion in common are placed in
the same solution, if no reaction occurs, the numbers of moles of the common
ion are added.
EXAMPLE 11.15
Calculate the concentration of each ion in a solution made by adding 41.4 mL
of 1.03 M NaCl to 66.2 mL of 0.818 M
CaCl
2
and diluting to 150.0 mL.
Solution
When these two solutions are combined, no chemical reaction takes place, but
the final chloride ion concentration includes the chloride ions provided by both
salts. The cation concentrations are not added because the cations are different.
The number of moles of each ion is calculated as follows:
Because no reaction takes place,
the numbers of moles of
Cl
ion
are merely added.
a
1.03 mmol NaCl
1 mL NaCl
41.4 mL NaCl
b
42.6
4
mmol NaCl
a
0.818 mmol CaCl
2
1 mL CaCl
2
66.2 mL CaCl
2
b
54.1
5
mmol CaCl
2
In
42.6
4
mmol of NaCl, there are
Na
Cl
42.6
4
mmol
and
42.6
4
mmol
In
54.1
5
mmol of
CaCl
2
,
there are
Cl
mmol Ca
2
108.
3
mmol
and
54.1
5
