1. Tardigrade
  2. Question
  3. Chemistry
  4. One gram of Na 3 AsO 4 is boiled with excess of solid Kl in presence of strong HCl. The iodine evolved is absorbed in Kl solution and titrated against 0.2 N hyposolution. Assuming the reaction to be AsO 43-+2 H ++2 I - longrightarrow AsO 33-+ H 2 O + I 2 calculate the volume of thiosulphate hypo consumed. [Atomic weight of As =75]

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Q. One gram of $Na _{3} AsO _{4}$ is boiled with excess of solid $Kl$ in presence of strong $HCl$. The iodine evolved is absorbed in $Kl$ solution and titrated against $0.2 N$ hyposolution. Assuming the reaction to be
$AsO _{4}^{3-}+2 H ^{+}+2 I ^{-} \longrightarrow AsO _{3}^{3-}+ H _{2} O + I _{2}$
calculate the volume of thiosulphate hypo consumed. [Atomic weight of $As =75]$

Redox Reactions

Solution:

image

molar mass $Na _{3} AsO _{4}=23 \times 3+75+16 \times 4=208$

eq. of $AsO _{4}^{-}=\frac{1}{\left(\frac{208}{2}\right)}=\left(\frac{1}{104}\right)$

equivalent of $Na _{3} AsO _{4}=$ equivalent of $I _{2}=$ equivalent of $Na _{2} S _{2} O _{3}$

$\frac{1}{104 \times .2} L=V=48.1 \,mL$