A compound contains 14.5 g of magnesium and 3.5 g of oxygen. What is the mass percent of oxygen in the compound?

(mass O/total mass)*100 = ?

19.44 19.44%

To find the mass percent of oxygen in the compound, we need to calculate the ratio of the mass of oxygen to the total mass of the compound.

Step 1: Calculate the total mass of the compound by adding the masses of magnesium and oxygen.
Total mass of the compound = mass of magnesium + mass of oxygen
Total mass of the compound = 14.5 g + 3.5 g
Total mass of the compound = 18 g

Step 2: Calculate the mass percent of oxygen by dividing the mass of oxygen by the total mass of the compound and multiplying by 100.
Mass percent of oxygen = (mass of oxygen / total mass of the compound) x 100
Mass percent of oxygen = (3.5 g / 18 g) x 100
Mass percent of oxygen = 0.1944 x 100
Mass percent of oxygen = 19.44 %

Therefore, the mass percent of oxygen in the compound is 19.44 %.