Calculate the oxidation number of underlined elements in the following species. ul(C)O_2 , ul(Cr_2)O_7^(2-) , ul(Pb_3) O_4 , ul(P)O_4^(3-)

Calculate the oxidation number of underlined elements in the following

1.	Calculate the oxidation number of underlined elements in the following species. ul(C)O_2 , ul(Cr_2)O_7^(2-) , ul(Pb_3) O_4 , ul(P)O_4^(3-)
Answer» Solution :1. C in `CO_2 `Let oxidation number of C be x. Oxidation number of each O ATOM = -2. Sum of oxidation number of all ATOMS = x+2 (-2) `implies`x - 4. As it is neutral MOLECULE, the sum must be equal to zero. `:.` x-4=0 (or) x= +4 2. `Cr " in " Cr_2O_7^(2-)`Let oxidation number of Cr = x. Oxidation number of each oxygen atom = -2. Sum of oxidation number of all atoms `2 x + 7(-2) = 2 x -14` Sum of oxidation number must be equal to the charge on the ion. THUS , 2x -14 =-2 ` 2x = + 12 ` `x = 12//2` `x = 6`