Question

HW : Ch 17 Part 2 (Butters, Titrations, Solubility &Complex lons) -3.4hrs)(52 credits Common-lon Effect on Solubility for Lead Thiocyanate 7 of 27 Review Constants Periodic Table Lead thiocyarate, Pb(SCN), has a 2.00 x 10-5 value of Part A Calculate the molar solubility of lead thiocyanate in pure water. The molar solby is the maximum amount of lead thiocyanate the solution can hold Express your answer with the appropriate units. View Available Hints) Value Units Submit Common on Effect Consider the dissolution of AB(): AB(s) A+ (aq) +B (n) Le Chinelor's principle tells us that an increase in either [ A B ] wish this equunto the left, reducing the soily of AB In other words, AB more soluble in pure water than in a solution that already contains A B ons. This is an example of the common in efect Part B Calculate the motor obity of Wad thiocyanate in so MKSCN Express your answer with the appropriate units. View Available Hint(e)

Answer 1

Part A

Solubility equilibrium of Pb(SCN)2

Pb(SCN)2(s) <-------> Pb²⁺(aq) + 2SCN^-(aq)

K_sp = [Pb²⁺][SCN^-]²= 2.00 ×10^-5

If solubility of Pb(SCN)2 is represented by S

at saturated solution

[Pb²⁺] = 1S

[SCN^-] = 2S

so,

(1S)(2S)² = 2.00 ×10^-5

4S³ = 2.00 × 10^-5

S³ = 5.00 × 10^-6

S = 0.0171M

Therefore,

Molar solubility of Pb(SCN)2 in pure water = 0.0171M

Part B

K_sp = [ Pb²⁺] [SCN^-]² = 2.00 × 10^-5

substitute given concentration of SCN^- ​​​​​​in K_sp expression

[Pb²⁺]( 0.100M)² = 2.00 ×10^-5M³

[Pb²⁺] = 2.00 × 10^-3M

Therefore

molar solubility of Pb(SCN)2 in 0.100M KSCN = 2.00 ×10^-3M