Question

Calculate the equivalent mass of potassium dichromate. The reduction half- reaction in acid medium is
Cr2O72-+14H+(2Cr3+ +7H2O

please explain with steps to solve​

Answer 1

Explanation:

Answer: Equivalent weight of K_2Cr_2O_7K2Cr2O7 in acidic medium is 49 g/eq.

Explanation: We are given an ionic equation of K_2Cr_2O_7K2Cr2O7 , which is

Cr_2O_7^{2-}+14H^++6e^-arrow 2Cr^{3+}+7H_2OCr2O72−+14H++6e−arrow2Cr3++7H2O

Molar mass of K_2Cr_2O_7K2Cr2O7 = (2 × 39) + (2 × 52) + (7 × 16)

Molar mass of K_2Cr_2O_7K2Cr2O7 = 294 g

Equivalent weight in a redox reaction is the molar mass divided by the number of electrons lost or gained in the reaction.

For, the above reaction:

Number of electrons lost = 6

Hence, the equivalent weight of K_2Cr_2O_7K2Cr2O7 is

\text{Equivalent weight of }K_2Cr_2O_7=\frac{294}{6}Equivalent weight of K2Cr2O7=6294

Equivalent weight of K_2Cr_2O_7K2Cr2O7 = 49 g/eq

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