Question

One gram of Na3AsO4 is boiled with excess of solid Kl in presence of strong HCI. The iodine evolved is absorbed in Kl solution and titrated against 0.2 N hyposolution. Assuming the reaction to be
AsO 3- + 2H+ + 2I- → (AsO3)³- + H2O + I²
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​

Answer 1

Answer:

48.1 ml

Explanation:

n-factor for As =5−3=2

Equivalent weight of Na 3 AsO4 =  208/2=104

Normality of Na 3 AsO4 =   mass /eq.wt =  1/104

we know that  (thiosulphate) N 1 V  1 =N  2 V2 (Na3  ASO 4  )

0.2×V  1 =  1/104 ×1000

v1 =48.1ml Ans