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09/12/2021 10:45 am
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A 5.0 mL solution of H2O2 liberates 1.27 g of iodine from an acidified KI solution. The percentage strength of H2O2 is
(a) 11.2
(b) 5.6
(c) 1.7
(d) 3.4
1 Answer
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09/12/2021 10:52 am
Correct answer: (d) 3.4
Explanation:
H2O2≡ KI ≡ I2
mEq of H2O2 = 5 × N
mEq of I2 = \(\frac{Weight}{E.w}\times 1000\)
\(\frac{1.27}{127}\times 1000\) = 10 mEq
I2 = M.w = 254
E.w = \(\frac{M.w}{2}\) = \(\frac{254}{2}\) = 127
∴ mEq of H2O2 = mEq of I2
5 x N = 10
∴ N = 2
1N of H2O2 = 1.7% of H2O2
2N of H2O2 = 3.4% H2O2