What is the chemical formula for cobalt (II) hydrogen carbonate?

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Answer 1 · 2017-02-10T01:04:49

The chemical formula for cobalt(II) hydrogen carbonate is #"Co"("HCO"_3)_2#.

The name tells you that this is an ionic compound, made of cobalt(II) ions and hydrogen carbonate ions.

The symbol for the cobalt(II) ion is #"Co"^"2+"#.

The symbol for the hydrogen carbonate ion is #"HCO"_3^"-"# (you have memorized the formulas of the polyatomic ions, haven't you?).

So, the formula contains #"Co"^"2+", "HCO"_3^"-"#.

We need two "-" charges to balance the "2+" charges on the #"Co"#.

Thus, we need two hydrogen carbonate ions, so we enclose the formula in parentheses followed by a subscript 2.

The formula is #"Co"("HCO"_3)_2#