Answer to Question #107396 in Organic Chemistry for Maow Abdullahi

Question

a) (i) Use EDTA structure to describe hexadentate chelating agent (2mks)
(ii) State four types of EDTA titrations (2mks)

b)ii)Consider the titration of 50mL Mg 2+ sample in a pH = 10.00 buffer with 0.05M EDTA as titrant. Calculate the amount of Mg in ppm if the titre is 5ml of EDTA (3mks)
ii) Calculate the pH of a 1000-mL buffer solution containing 0.200M NH4OH and 0.300M NH4CI. (3mks)

Answer 1

a) I. A hexadentate ligand in coordination chemistry is a ligand that combines with a central metal atom with six bonds. (Picture: generic structure of a metal complex of hexadentate EDTA)

II. Acid-base titrations

Redox titrations

Complexometric titrations

Precipitation titrations

b) I. C_Mg = 24 × 0.05 / 10 × 10³ = 120 ppm

II. pH = pK_a + lg(a_NH4OH / a_NH4Cl) = 9.25 + lg(0.2 / 0.3) = 8.67