How would you determine the volume of an object if you were given its mass and density?

Density = mass / volume

To solve for volume, multiply both sides of the equation by volume. This will cancel volume on the right and place it on the left.

volume x density = mass / volume x volume

volume x density = mass

Now, divide both sides by the density.

volume x density / density = mass / density

In the end, density cancels out so:

Volume = mass / density

It will appear as o2(g) as a reactant