1. If Qsp < Ksp, shift to products, no precipitate forms
Chemical Equilibrium: Additional Concepts
Let’s see it again…
If Qsp < Ksp, shift to products, no precipitate forms
If Qsp > Ksp, shift to reactants, precipitate will form
If Qsp = Ksp, no change will occur
From your HW, #69

2. Q 69) Will a precipitate form when 1. 00 L of 0
Q 69) Will a precipitate form when 1.00 L of M iron (II)chloride solution is mixed with 2.00 L of M sodium hydroxide solution? Ksp = 4.9x10-17
Calculate Q
1)Q expression
FeCl2(aq) + 2NaOH(aq) Fe(OH)2(s) + 2NaCl(aq)
Fe(OH)2(s) Fe2+(aq) + 2OH-(aq)
Qsp = [Fe2+] [OH-]2

3. Q 69) Will a precipitate form when 1. 00 L of 0
Q 69) Will a precipitate form when 1.00 L of M iron (II)chloride solution is mixed with 2.00 L of M sodium hydroxide solution? Ksp = 4.9x10-17
Calculate Q
2) Molarities:
[Fe2+] [OH-]
.150 M M
Ratio total volume:
1 L = L = 2
3 L L

4. Q 69) Will a precipitate form when 1. 00 L of 0
Q 69) Will a precipitate form when 1.00 L of M iron (II)chloride solution is mixed with 2.00 L of M sodium hydroxide solution? Ksp = 4.9x10-17
Calculate Q
2) Molarities
[OH-] = 2/3 ( M) = M
[Fe2+] = 1/3 (0.150 M ) = 0.05 M
Ratio of total volume

5. Q 69) Will a precipitate form when 1. 00 L of 0
Q 69) Will a precipitate form when 1.00 L of M iron (II)chloride solution is mixed with 2.00 L of M sodium hydroxide solution? Ksp = 4.9x10-17
Calculate Q
3) Solve!
4) Compare:
Qsp = [Fe2+] [OH-]2
= [0.05M] [0.0222M]2
= 2.46x10-5
Qsp (2.46x10-5) Ksp(4.9x10-17)
So… shift to reactants
precipitate will form
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