15.0 g of potassium chlorate is melted so that it will then decompose. What mass of oxygen is produced assuming all of the original potassium chlorates fully decomposes?

5.875 g of Oxygen

Explanation:

We must first balance our decomposition equation KClO3 -> K + ClO3

The amount of oxygen in CLO3 is 3 times the original. We begin by converting 15g of KClO3 to moles. 15 / (39.1 + 35.45 + 3(16) ) = 0.122 mols.

Then we go to moles of oxygen,

.122 * 3 = 0.367 mols of Oxygen

Then to grams of Oxygen

.367 * 16 = 5.875 g

it is the most commonly accepted one