What is the oxidation state of chromium in the dichromate ion, #"Cr"_2"O"_7^(2-)#?

1 Answer

Answer:

+6

Explanation:

Problem: What is the oxidation number (O.N.) of chromium (Cr) in the dichromate ion #"Cr"_2"O"_7"^(2-)#?

Let the O.N. of Cr be #x#. The O.N. of oxygen is -2.

The sum of the oxidation states in an ion must add up to the charge on the ion. The dichromate ion has a charge of #"2"^-#, as indicated by its formula, #"Cr"_2"O"_7"^(2-)#.

#2*x# + #7*#(-2) = (-2)

#2*x# - 14 = -2

Add 14 to both the sides;

#2*x# -14 +14 = -2 +14

#2*x# = 12

Divide both sides by 2 ;

#"2x"/2"# =#"12"/"2" #

#x = 6#

The oxidation number of chromium in the dichromate ion is #+6#.

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