Question

How many grams of magnesium oxide can be produced when 97.2 g Mg react with 88.5 g O2?

Unbalanced equation: Mg + O2 → MgO

Answer 1

csiagentMg + O2 → MgO

Well you see that there are 2 oxygens on the reactant side while there is only 1 oxygen on the product side. To balance the oxygen, you can multiply the MgO on the product side by 2. So you have

Mg + O2 → 2MgO

Now if you take a look at the Magnesiums, there are 2 on the product, but only 1 on the reactant. You can multiply the magnesium on the reactant side by 2 to get both sides to equal with respect to magnesium.

2Mg + O2 → 2MgO

Are there equal amounts of each atom on both sides? Yes! That is the final balanced equation.

So 2Mg + O2 ---> 2MgO is the balanced equation.