# Math Help - oxidation

1. ## oxidation

Determine the oxidation number of the specified element.
Cr in CrO4 $^2-$

2. Originally Posted by johett
Determine the oxidation number of the specified element.
Cr in CrO4 $^2-$
well this is not math xD

but I know the answer, I think that you mean:

$
CrO_4^{ - 2}
$

to answer this problem you must know that, the oxidation number of oxigen y -2, then we have this equation:

$
Cr + 4 \cdot - 2 = - 2 \Leftrightarrow \boxed{Cr = 6}
$