Precipitation Titration Lecture Notes PDF

Precipitation titration 9thlecture Prepared by Dr. Ahmed Bahgat What is the difference between solution, suspension and precipitate? Solubility product constant (Ksp): It is the product of the concentration of the ions that are present in a saturated solution of an ionic compound F...

Precipitation titration 9thlecture Prepared by Dr. Ahmed Bahgat What is the difference between solution, suspension and precipitate? Solubility product constant (Ksp): It is the product of the concentration of the ions that are present in a saturated solution of an ionic compound For a salt AaBb AaBb (solid) → a A+ + b B- Ksp = [A+]a. [B-]b. Examples: For AgCl Ksp = [Ag+].[Cl-] For Pb3(PO4)2 KSP = [Pb2+]3.[PO43-]2 Ksp represents the level at which a solute dissolves in solution. The more soluble a substance is, the higher the Ksp value it has. Copper(I) bromide has a measured molar solubility of 2.20x10-4 mol/L at 25°C. calculate its K value. sp CuBr = Cu+ + Br- (s) (aq) (aq) X X X K = [A]a[B]b sp K = [Cu+] [Br-] = [2.20x10-4 mol/L] [2.20x10-4 mol/L] = 4.0x10-8 mol2/L2 (units for K are usually omitted). sp sp Calculate the K value for bismuth sulfide (Bi S ), which has a solubility of 1.0x10-15 mol/L at 25°C. sp 2 3 Bi S 2Bi3+ + 3S2- 2 X 3(s) 2X (aq) 3X (aq) K = [2X]2. [3X]3 Ksp = [2x1.0x10-15]2.[3 x 1.0 x10-15]3 = 1.1 x 10-73 sp A solution is 1.5 x 10–6 M in Ni2+. Na2CO3 is added to make the solution 6.0 x 10–4 M in CO32–. Ksp(NiCO3) = 6.6 x 10–9. Will NiCO3 ppt? Answer NiCO3  Ni2+ + CO32– Reaction quotient Q = [Ni2+][CO32–] = [1.5 x 10–6][6.0 x 10–4] = 9.0 x 10–10 Q < Ksp No precipitate will be formed A solution contains 0.001 M of KI and 0.10 M of KCl. AgNO3 is gradually added to this solution. Which forms first, solid AgI or solid AgCl? Ksp (AgCl)=1.6×10−10 ; Ksp (AgI) =1.5×10−16 Learning Quiz 1. For Pb3(PO4)2, KSP = A. 3[Pb2+]3.2[PO43-]2 B. 3[Pb ].2[PO4 ] 2+ 3- C. [Pb ].[PO4 ] 2+ 3 3- 2 2. Calculate the solubility of Zn(OH)2 in mg/L? Ksp = 4.5 x10-17 (M.Wt of Zn(OH)2 = 99.4) (answer 0.223 mg/L).  ◼ Experiment 9 ◼ Redox Titration Standardization of potassium permanganate and determination of iron Standardization of KMnO4 Procedure: 1- 1) Transfer 10 ml oxalic acid solution (0.1 M) into a conical flask and add 20 ml, 2N H2SO4. 2) Heat the solution to 60-70 C and titrate slowly with potassium permanganate to the faint pink colour end-point. 3) Repeat the titration another two times. Standardization of KMnO4 (MV)\5oxalic = (MV)\2KMnO4 Standardization of KMnO4 Procedure: 1- 1) Transfer 10 ml iron solution into a conical flask and add 20 ml, 2N H2SO4. 2) Titrate slowly with potassium permanganate to the faint pink colour end-point. 3) Repeat the titration another two times. Standardization of KMnO4 (MV)\5 Iron = (MV)\1KMnO4  Quiz 1- Find the number of millimoles of solute in 537 mL of 0.0200 M KOH? 2- What is the mass in grams of solute in 37.0 mL of 5.75 x 10-4 M benzoic acid (122 g/mol)? 3- Calculate the pH of nitric acid (0.1 M)? Calculate the pOH of ammonium chloride (0.05 M) (Kb= 1.1 X 10-6)? 4- Define A- Oxidizing agent B- Reduction C- F test D- Q test 5- A 5ml of 1.5g/ml NaOH was diluted with water to 15ml. Calculate the final concentration? 6- The nitric acid don’t utilize in standardization of potassium permanganate (Give reason)?