Concentration of Ions in
Solution
Chapter 5
Lesson 9
Ions
 Recall that a solution of copper (II) nitrate
is blue. Why? Discuss with a neighbor.
 Copper (II) ions are blue. See back of
periodic table for other examples.
 The darker the blue color we see would
indicate that there are more ions in such a
solution. It is often desirable to calculate
the concentration of the ions. This is done
much the same as any other calculation of
concentration.
Flame tests
 Ions have characteristic colors when burned.
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Concentration
 What is the concentration of copper (II)
ions in a 0.75 mol/ L solution of copper (II)
nitrate?
 Step 1: Write the dissociation equation.

Cu(NO3)2 (s) ---> Cu2+ (aq) + 2NO3- (aq)
 Step 2: Calculate the concentration.

C Cu2+ = # of mol of ion
x con. of
solution

# of mol of cmpd
 What is the concentration of the nitrate
ions in the above solution?
Example
 We are given 26.3 g of iron (III) oxide and
dissolve this in enough water to make 500
mL of solution. What is the concentration
of each ion in the solution?
 Step 1: Calculate the moles of iron (III)
oxide.
 Step 2: Calculate the concentration of the
solution.
 Step 3: Write the dissociation equation.
 Step 4: Calculate the ion concentrations.
Example
 What mass of ammonium sulfate is
required to produce a 200 mL solution
with a 1.24 mol/L concentration of
ammonium ions?
 Step 1: write dissociation equation.
 Step 2: calculate the concentration of the
solution. (what is needed / what is given)
 Step 3: calculate the number of moles
needed
 Step 4: calculate the mass required.
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Assignment
 P. 193 #17-22
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