Solubility Lesson 5 Trial Ion Product

We have learned that when two ionic solutions are mixed and if one product has low solubility, then there is a reaction where a precipitate will form. Pb(NO 3 ) 2(aq) + 2NaCl (aq) → PbCl 2(s) + 2NaNO 3(aq) low solubility The solubility chart on page 4 predicts this reaction, but only if the solution is 0.10 M or greater. If the molarity is less than 0.10 M, then the reaction may or may not happen. A trial ion product must be calculated to predict the reaction of all solutions less than 0.10 M.

The capacity of a solution to dissolve a solid is described by the Ksp. PbCl 2(s) ⇌ Pb 2+ +2Cl - The Ksp represents the limit of the solution to dissolve PbCl 2. You can add Pb 2+ and Cl - until the ion concentrations are equal to the Ksp. The solution is saturated and addition PbCl 2 must sit on the bottom not dissolved. Pb 2+ 2Cl - Pb(NO 3 ) 2 NaCl

mL 0.10 M Pb(NO 3 ) 2 is mixed with mL of 0.20 M NaCl, will a precipitate occur?

PbCl 2(s) ⇌ Pb 2+ +2Cl - Write a dissociation equation for the compound with low solubility.

mL 0.10 M Pb(NO 3 ) 2 is mixed with mL of 0.20 M NaCl, will a precipitate occur? PbCl 2(s) ⇌ Pb 2+ +2Cl M0.20 M Write a dissociation equation for the compound with low solubility. List the initial molarities of each ion.

mL 0.10 M Pb(NO 3 ) 2 is mixed with mL of 0.20 M NaCl, will a precipitate occur? PbCl 2(s) ⇌ Pb 2+ +2Cl M M M0.12 M Write a dissociation equation for the compound with low solubility. List the initial molarities of each ion. Reduce each molarity by the dilution factor: V 1 /V 2.

mL 0.10 M Pb(NO 3 ) 2 is mixed with mL of 0.20 M NaCl, will a precipitate occur? PbCl 2(s) ⇌ Pb 2+ +2Cl M M M0.12 M TIP=[Pb 2+ ][Cl - ] 2 TIP=[0.040][0.12] 2 =5.8 x Write a dissociation equation for the compound with low solubility. List the initial molarities of each ion. Reduce each molarity by the dilution factor: V 1 /V 2. Write the Ksp or TIP (trial ion product) and solve.

mL 0.10 M Pb(NO 3 ) 2 is mixed with mL of 0.20 M NaCl, will a precipitate occur? PbCl 2(s) ⇌ Pb 2+ +2Cl M M M0.12 M TIP=[Pb 2+ ][Cl - ] 2 TIP=[0.040][0.12] 2 =5.8 x Ksp=1.2 x TIP > Ksp ppt forms Write a dissociation equation for the compound with low solubility. List the initial molarities of each ion. Reduce each molarity by the dilution factor: V 1 /V 2. Write the Ksp or TIP (trial ion product) and solve. Compare to real Ksp

2. Will a precipitate form if 20.0 mL of 0.010M CaCl 2 is mixed with 60.0 mL of M Na 2 SO 4 ? CaSO 4(s) ⇌ Ca 2+ +SO M M M M TIP=[Ca 2+ ][SO 4 2- ] TIP=[0.0025][0.0060] =1.5 x Ksp=7.1 x TIP < Ksp no ppt forms

AgCl (s) ⇌ Ag + +Cl M M M TIP=[Ag + ][Cl - ] TIP=[0.020][0.020] =4.0 x Ksp=1.8 x TIP > Ksp ppt forms The Cl - is doubled 3.Will a precipitate form when equal volumes of M CaCl 2 and M AgNO 3 are mixed.

4.Consider the two saturated solutions AgCl and Ag 2 CrO 4. Which has the greater Ag + concentration? AgCl ⇌ Ag + + Cl - Ag 2 CrO 4 ⇌ 2Ag + + CrO 4 2- ssss2s s Ksp=s 2 Ksp=4s x = s x =4s 3 s = 1.3 x Ms = 6.5 x M [Ag + ] = 1.3 x M[Ag + ] = 2s = 1.3 x M Ag 2 CrO 4 has the greater Ag + concentration