Question

For questions 17 and 18. A solution is prepared by mixing 150.0 mL of 1.0 x 10 M AgNO3 with 200mL of 5.0M Na S O The stepwise formation equilibria are Ag +S203 Ag (S2O3) Ag(S2O3) +S20, Ag(S20s)2 17. What is the concentration of Ag(S203) in solution (5 points): A. 3.8x 10 B. 1.8 x 10 18 C. 4.3x 10 D. 5.6 x 10 K1 7.4 x 10 K2 3.9 x 104

Answer 1

Initial moles of Ag⁺ = Concentrationx Volume in Liter = 1 x 10^-3 M x 0.15 L= 1.5 x 10^-4 moles

Initial moles of S₂O₃^2- = Concentrationx Volume in Liter = 5 M x 0.2 L= 1 moles

Total volume = 350 mL = 0.35 L

Therefore, concentration of Ag(S₂O₃)₂^-3 in the solution = Moles/ Volume in liter

                                                                                     = (1.5 x 10^-4 moles) / 0.35 L

                                                                                      = 4.29 x 10^-4 M

Concentration of S₂O₃^2- in the solution = Moles/ Volume in liter

                                                                       = (1 M) / 0.35 L = 2.86 M

Now,

K₂ = [Ag(S₂O₃)₂^-3]/ {[Ag(S₂O₃)₂^-1][S₂O₃²]} = 3.9 x 10⁴

[4.29 x 10^-4]/ {[Ag(S₂O₃)₂^-1][2.86 M]} = 3.9 x 10⁴

[Ag(S₂O₃)₂^-1] = 3.8 x 10^-9 M