1. Tardigrade
  2. Question
  3. Chemistry
  4. To a 10 ml, 1M aqueous solution of Br2 , excess of NaOH is added so that all Br2 is disproportionated to Br- and BrO3- . The resulting solution is made free of Br- by extraction and excess of OH- is neutralised by acidifying the solution. The resulting solution is sufficient to react with 2g of impure CaC2O4 (M = 128 g/mole) sample. Which of the following is the correct % purity of oxalate sample

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Q. To a 10 ml, 1M aqueous solution of $Br_{2}$ , excess of NaOH is added so that all $Br_{2}$ is disproportionated to $Br^{-}$ and $BrO_{3}^{-}$ . The resulting solution is made free of $Br^{-}$ by extraction and excess of $OH^{-}$ is neutralised by acidifying the solution. The resulting solution is sufficient to react with 2g of impure $CaC_{2}O_{4}$ (M = 128 g/mole) sample. Which of the following is the correct % purity of oxalate sample

NTA AbhyasNTA Abhyas 2020Some Basic Concepts of Chemistry

Solution:

Solution

$6 H ^{+}+ BrO _{3}^{-}+3 C _{2} O _{4}^{2-} \rightarrow Br ^{-}+6 CO _{2}+3 H _{2} O$

$10 / 3 m$ mole $BrO _{3}^{-}$ reacts with $10 m$. mole $C _{2} O _{4}^{2-}$

Mass of $CaC _{2} O _{4}=10 \times 10^{-3} \times 128=1.28 g$

$\%$ purity $=\frac{\text { Weight of substance }}{\text { Weight of compound }} \times 100$ $\%$ purity $=\frac{1.28}{2} \times 100=64 \%$