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What is the equivalent mass of potassium dichromate ( ) when it acts as an oxidizing agent in a stroRedox Reactions and Volumetric Analysis Chemistry Question

Question

What is the equivalent mass of potassium dichromate ( $K_2Cr_2O_7$ ) when it acts as an oxidizing agent in a strongly acidic medium, assuming its molar mass is identically $M$ ?

Answer: C

💡 Solution & Explanation

The relevant reduction half-reaction for the potassium dichromate ion in an acidic medium is mathematically $Cr_2O_7^{2-} + 14H^+ + 6e^- \to 2Cr^{3+} + 7H_2O$ . The oxidation state of Chromium drops from $+6$ to $+3$ , representing a difference of $3$ electrons per atom. Since there are inherently two Cr atoms embedded in one single dichromate unit, the total number of electrons gained per molecule is $2 \times 3 = 6$ . The definitive n-factor is 6, making the equivalent mass $M/6$ .

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