Question

The concentration of Sn2+ in a solution is determined by titration with a 0.1650 M permanganate solution. The balanced net ionic equation for the reaction is:

2MnO4-(aq) + 5Sn2+(aq) + 16H3O+(aq) 2Mn2+(aq) + 5Sn4+(aq) + 24H2O(l)

(a) If 15.75 mL of the 0.1650 M permanganate solution are needed to react completely with 30.00 mL of the Sn2+ solution, what is the concentration of the Sn2+ solution? _________M

(b) Which of the two solutions was in the buret during the titration?

(c) Suppose at the end of the titration, the solution containing the Mn2+ ion is transferred to a volumetric flask and diluted to 400. mL. What is the concentration of Mn2+ in the diluted solution? ________M

Answer 1

2MnO4-(aq) + 5Sn2+(aq) + 16H3O+(aq) -------------------->2Mn2+(aq) + 5Sn4+(aq) + 24H2O(l)

2 moles          5 moles

MnO4^-                                                                           Sn^+2

M1 = 0.165M                                                                M2 =

V1 = 15.75ml                                                                V2   = 30ml

n1   = 2                                                                         n2 = 5

      M1V1/n1     =     M2V2/n2

       M2               = M1V1n2/n1V2

                         = 0.165*15.75*5/2*30   = 0.2165M

Conc of Sn^+2   = 0.2165M

b. KMnO4 solution taken in the buret.

c.

Initial                                                   Fianl

M1 = 0.165M                                        M2 =

V1   = 15.75ml                                        V2 = 400ml

   M1V1 = M2V2

   M2 = M1V1/V2

           = 0.167*15.75/400   = 0.0066M