Transcript File

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
Q 69) Will a precipitate form when 1.00 L of 0.150
M iron (II)chloride solution is mixed with 2.00 L of
0.0333 M sodium hydroxide solution? Ksp = 4.9x10-17
Calculate Q
FeCl2(aq) + 2NaOH(aq)
Fe(OH)2(s)
1)Q expression
Fe(OH)2(s) + 2NaCl(aq)
Fe2+(aq) + 2OH-(aq)
Qsp = [Fe2+] [OH-]2
Q 69) Will a precipitate form when 1.00 L of 0.150
M iron (II)chloride solution is mixed with 2.00 L of
0.0333 M sodium hydroxide solution? Ksp = 4.9x10-17
Calculate Q
2+]
-]
[Fe
[OH
2) Molarities:
.150 M
.0333 M
Ratio total volume:
1L =1
2L =2
3L
3
3L
3
Q 69) Will a precipitate form when 1.00 L of 0.150
M iron (II)chloride solution is mixed with 2.00 L of
0.0333 M sodium hydroxide solution? Ksp = 4.9x10-17
Calculate Q
2) Molarities
[OH-] = 2/3 (0.0333 M) = 0.0222 M
[Fe2+] = 1/3 (0.150 M ) = 0.05 M
Ratio of total volume
Q 69) Will a precipitate form when 1.00 L of 0.150
M iron (II)chloride solution is mixed with 2.00 L of
0.0333 M sodium hydroxide solution? Ksp = 4.9x10-17
Calculate Q
3) Solve!
Qsp = [Fe2+] [OH-]2
= [0.05M] [0.0222M]2
= 2.46x10-5
4) Compare:
Qsp (2.46x10-5) > Ksp(4.9x10-17)
So… shift to reactants
precipitate will form