How do you work out the oxidation number of an element in a compound? E.g finding the oxidation number of the element Cr from the compound #Cr2O3#

1 Answer
Jan 8, 2018

The overall compound has a no charge (neutral). That means the positive and negative charges are equal in number. For the compound #Cr_2 O_3#, Chromium is a metal and hence its oxidation number is positive, lets say +x is its oxidation number. The oxidation number of oxygen is already known i.e -2. So, we can write an equation, as

#2* (+x) + 3* (-2) = 0#
(We equate it to zero because he overall charge is 0)

or 2#x-6 = 0#

or #2x= +6#

or # x = +3#