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

Options

  1. A84.3%
  2. B32.5%
  3. C60%
  4. D64%

Correct answer

D. 64%

Step-by-step solution

6 H + + B r O 3 - + 3 C 2 O 4 2 - → B r - + 6 C O 2 + 3 H 2 O 10/3 m mole B r O 3 - reacts with 10 m. mole C 2 O 4 2 - Mass of CaC 2 O 4 = 10 × 10 − 3 × 128 = 1 .28 g % purity = Weight of substance Weight of compound × 100 % purity = 1.28 2 × 100 = 64 %

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