Question

The cation of this ionic compound has 11 protons. The polyatomic anion has three oxygens, a charge of -1, and goes by two different names. This product is often used in the kitchen to make tasty treats. What’s the compound’s name and formal?

Answer 1

Baking soda, `"NaHCO"_3`.

Explanation:

Right from the start, you know that the cation of this ionic compound is the sodium cation, `"Na"^(+)`.

You can make this claim because the number of protons present in the nucleus of the neutral atom will also be present in the nucleus of the ion, and since sodium is the element that has an atomic number equal to `11`, i.e. `11` protons inside the nucleus, you can say that you're dealing with the sodium cation.

Now, a polyatomic ion that has `3` atoms of oxygen, a `1-` net charge, and goes by two different names is the bicarbonate anion, `"HCO"_3^(-)`, which is also known as the hydrogencarbonate anion.

This implies that this unknown compound is sodium bicarbonate, `"NaHCO"_3`, which is also known as baking soda. Indeed, this compound is used extensively in cooking as a leavening agent `->` see here.