Question #5dec3

1 Answer
Ernest Z.
May 17, 2017

The equivalent mass of #"K"_2"Cr"_2"O"_7# is 49.03 g.

Explanation:

The equivalent mass of a substance is the mass that will supply or react with one mole of electrons in a redox reaction.

The half-reaction for the dichromate ion is

#"Cr"_2"O"_7^"2-" + "14H"^"+" + "6e"^"-" → "2Cr"^"3+" + 7"H"_2"O"#

1 mol of #"Cr"_2"O"_7^"2-"# reacts with 6 mol of electrons, so

1 mol of #"K"_2"Cr"_2"O"_7# reacts with 6 mol of electrons

∴ #"Equivalent mass of K"_2"Cr"_2"O"_7 = "molar mass"/6 = "294.18 g"/6 = "49.03 g"#

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