Question

18. A. When 12.0 mL of a 9.46×10^-4 M copper(II) sulfate solution is combined with 12.0 mL of a 9.55×10^-4 M potassium hydroxide solution does a precipitate form? _______ (yes or no)

For these conditions the Reaction Quotient, Q, is equal to _______.

B. When 18.0 mL of a 5.83×10^-4 M lead acetate solution is combined with 25.0 mL of a 7.75×10^-4 M potassium carbonate solution does a precipitate form? _______ (yes or no)

For these conditions the Reaction Quotient, Q, is equal to ______.

C. When 25.0 mL of a 5.05×10^-4M sodium sulfide solution is combined with22.0 mL of a 4.04×10^-4M nickel(II) iodide solution does a precipitate form? ______ (yes or no)

For these conditions the Reaction Quotient, Q, is equal to _______.

Answer 1

18)

concentration of CuSO4 = 12.0 x 9.46 x 10^-4 / 12 + 12

                                       = 4.73 x 10^-4 M

concentration of KOH = 12.0 x 9.55 x 10^-4 / 12 + 12

                                    = 4.775 x 10^-4 M

Cu(OH)2 ------------> Cu2+    +    2 OH-

Q = [Cu2+][OH-]^2

    = (4.73 x 10^-4 ) (4.775 x 10^-4)^2

Q = 1.08 x 10^-10

Ksp = 1.6 x 10^-19

here Q > Ksp. so

yes , precipitate will form

Reaction Quotient, Q, = 1.08 x 10^-10

B)

concentration of Pb(CH3COO)2 = 2.44 x 10^-4

concentration of K2CO3 = 4.51 x 10^-4 M

PbCO3 ------------> Pb2+ +   CO32-

Q = 1.1 x 10^-7

Ksp = 1.5 x 10^-13

yes , precipitate will form

reaction quotient = 1.10 x 10^-7

C)

[Na2S] = 2.686 x 10^-4 M

[NiI2] = 1.89 x 10^-4 M

NiS ------------> Ni2+ + S2-

Q = 5.08 x 10^-8

Ksp = 3.0 x 10^-21

yes , precipitate will form

reaction quotient Q = 5.08 x 10^-8