Question

You heat 51 grams of magnesium over a Bunsen burner for several minutes until it reacts with oxygen in the air. Then you weigh the resulting product and see that it is now 53 grams. How does this happen without breaking the Law of Conservation of Mass?

Answer 1

I’m assuming that it isn’t an isolated system, if the magnesium reacts with the oxygen in the air it will form magnesium oxide
Due to the fact that it underwent a reaction(the addition of oxygen) the mass will therefore increase because of the additional element.

Answer 2

Answer: 2 grams of oxygen is reacted with magnesium.

Step-by-step explanation:

Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.

This also means that total mass on the reactant side must be equal to the total mass on the product side.

The chemical equation for the reaction of magnesium and oxygen follows:

`2Mg+O_2\rightarrow 2MgO`

Let the mass of oxygen be 'x' grams

We are given:

Mass of magnesium = 51 grams

Mass of magnesium oxide = 53 grams

Total mass on reactant side = 51 + x

Total mass on product side = 53

So, by applying law of conservation of mass, we get:

`51+x=53\\\\x=2g`

Hence, 2 grams of oxygen reacts with the given amount of magnesium.