is conjugate base of hydrogencarbonate carbon oxoanion carbonate A carbon oxoanion that has formula CO3. BVKZGUZCCUSVTD-UHFFFAOYSA-L CARBONATE ION CO3 CO3(2-) InChI=1S/CH2O3/c2-1(3)4/h(H2,2,3,4)/p-2 Karbonat [CO3](2-) [O-]C([O-])=O carbonate trioxidocarbonate(2-)