The equivalent weights of oxidising and reducing agents can be calculated by the number of electrons gained or lost. The equivalent weight of an oxidising agent is the number of parts by weight of the substance which gains one electron. Thus, it is equal to the molecular weight of the substance divided by the number of electrons gained in the balanced chemical equation. Similarly, equivalent weight of a reducing agent is equal to the molecular weight divided by the number of electrons lost as represented in the balanced chemical equation
The equivalent weight of barium in `BaCrO_4` used as an oxidising agent in acidic medium is (At, wt, of Ba - 137.34)

Options

A. 137.34
B. 45.78
C. 114.45
D. 68.67

Answer

B

Explanation

In acidic medium `BaCrO_4` is converted into
`BaCr_(2) O_(7) 2CrO_(4)^(2-) +2H^(+) rarr Cr_(2)O_(7)^(2-) +H_2O`
`CrO_(7)^(2-) +14H^(+) +6e^(-) rarr 2Cr^(3+) +7H_2O`
`2CrO_(4)^(2-) +16H^(+) +6e^(-) rarr 2Cr^(3+) +8H_(2)O`
Thus `2 BaCrO_(4)-= 6e^(-) ` or `BaCrO_4 -=3e^(-)`
`:.` Eq. wt of `Ba^(2+) =1/3 xx"At . wt"`
`=1/3 xx 137.34 = 45.78`