a. c C. QUESTION 3 EDTA titrations can be performed in many ways. Briefly describe the indirect OR displacement titration technique related to EDTA determination. 131 b. A small sample of powdered milk weighing 1.450 g was mixed with an aqueous buffer of pH 11.5. a few drops of calgamite indicator were added and the solution required 31.62 mL of 0.01538 M EDTA to reach the endpoint colour change. Calculate the % Ca in the milk. 131 Discuss the underlying principle of the potentiometric electroanalytical technique. 161 d. A 25.0 mL sample ontaining 0.0200 M Cd2+ was titrated with 0.0200 M EDTA at pH = 11.0. Calculate pd after the addition of 0.00,31.25 and 45.00 mL EDTA. Kear=2.9 x 10'; a = 0.85 151 Using any suitable example, explain how a substance can be quantitatively determined via the volatilization gravimetric method of analysis. 131 f. Outline the following occurrences in gravimetric techniques: i. Nucleation and surface adsorption 12.5 ii. Accomplishing larger particle size by coagulation of colloidal particles. 12.51 Total = 25 marks