11) One gram of Na3AsO4 is boiled with excess of solid KI in presence of strong HCI The iodine - Chemistry - General Principles and Processes of Isolation of Elements

Question

11) One gram of N a 3 A s O 4 is boiled with excess of solid KI
in presence of strong HCI The iodine evolved is absorbed in KI
solution and titrated against 0 2 N hypo solution Assuming the
reaction to be A s O 4 3 - + 2 H + 2 I → A s O 3 3 - + H 2 O
+ I 2
calculate the volume of hypo consumed [Atomic weight of As =
75]
(A) 48 1 mL
(B) 38 4 mL

(C) 24 7 mL

(D) 30 3 mL

Geetha · Accepted Answer

Volume of thio ≡Volume of I2 ≡ Volume of KI ≡ Volume of Na3AsO4Molecular mass of Na3AsO4 =3 × 23 + 75 + 4 × 16 = 208 gn factor = 2 (as the oxidation state changed from + 5 to +3)Equivalent mass of Na3AsO4 = 2082 = 104Normality of Na3AsO4 =1104 As per volumetric principleV1N1 = V2N2Volume of Na3AsO4  = 1 L = 1000 mlNormality of Na3AsO4 =1104Volume of thio = ?Normality of thio = 0
2 N1000 × 1104 = V2 × 0
2 V2 = 1000 × 1104 0
2 = 48 0769 ml    = 48
1 ml