If 15.6 grams of titanium reacts with oxygen to form 20 grams of titanium oxide what is the mass of oxygen that reacted?

Explanation:

In order to do this, we need first to write the chemical equation that is taking place which is the following:

Ti + O₂ > TiO₂

As we can see, the equation is perfectly balanced so, moles of Ti are the same moles TiO₂

To get the grams of O₂, in this simple question, we just need to apply the conservation of mass law, which states that the sum of the mass of the reactants, should be equal to the total mass of the product.

So, if we produced 20 g of TiO₂, which is the only product, then, the sum of the mass of Titanium and oxygen should give 20 g too. So, if we have 15.6 g of Titanium, then the mass of Oxygen:

mO₂ = 20 - 15.6

mO₂ = 4.4 g

This is the mass required to react with Titanium to produce the TiO₂.