In: Chemistry
Determine the oxidation state of the atoms indicated in the molecules below in the space provided:
Oxidation state of H = _________
Oxidation state of P = __________
Oxidation Number
a. LiAlH4
LiAlH4 is lithium aluminium hydride. Oxidation number of hydrogen in hydride is -1. Since aluminium and Lithium both are metals, they will have their oxidation numbers to be +1 since Li belongs to first group and Al will be assigned +3 which is obtained by equating the net charge on the compound to be zero and taking the Aloxidation number to be unknown. It is an exceptional case that though Hydrogen is assigned +1 oxidation state in most of the cases, in case of metal hydrides, it is assigned -1 oxidation state.
b. (NH4)3PO4
(NH4)3PO4 is ammonium phosphate. In ammonium, N has an oxidation number of -3, H is assigned +1. In phosphate O is assigned -2. Let the oxidation state of P be x
The net charge on a salt =o
3N + 12H + x + 4O = 0
(3*-3) + (12*1) + x + (4*-2) = 0
-9+12+x-8 =0
x= +5
So oxidation state of P in (NH4)3PO4 is +5