Question

Cobalt, a transition metal, forms both the Co2+ and Co3+ ions. Which of the following are the correct formulas and names for the oxides formed by the two different ions? (You’ll have to choose more than one)
a) CoO3, cobalt(III) oxide
b) CoO3, cobalt(II) oxide
c) Co2O3, cobalt(III) oxide
d) CoO3, cobalt(II) oxide
e) CoO3, cobalt(III) trioxide
f) CoO, cobalt(II) oxide
g) Co2O, cobalt(II) oxide
h) Co2O, cobalt(III) oxide

Answer 1

Well to solve this problem, we must remember that Oxygen in ionic form is Oxide O2- (an electric charge of negative 2). Hence the correct formulas and names taking into account the charge of Oxygen are:

c) Co2O3, cobalt(III) oxide

f) CoO, cobalt(II) oxide