Final answer:
The theoretical mass percentage of oxygen in potassium chlorate (KClO₃) is approximately 39.17%, which is not listed among the given choices. The percentage is calculated by dividing the mass of oxygen by the molar mass of the compound and then multiplying by 100%.
Step-by-step explanation:
Calculating Mass Percentage of Oxygen in Potassium Chlorate (KClO₃)
To find the theoretical mass percentage of oxygen in potassium chlorate, we must know the molar masses of both the compound and oxygen. Potassium chlorate (KClO₃) has a molar mass of approximately 122.55 g/mol (39.10 g/mol for K, 35.45 g/mol for Cl, and 16.00 g/mol for each O, multiplied by three since there are three oxygen atoms). To find the percentage of oxygen, we divide the total mass of oxygen in the compound by the molar mass of the compound and then multiply by 100%.
Mass of oxygen in KClO₃ = 3 × 16.00 g/mol = 48.00 g/mol
Percentage of oxygen = (48.00 g/mol / 122.55 g/mol) × 100% ≈ 39.17%
Thus, none of the provided options correctly represents the theoretical mass percentage of oxygen in potassium chlorate. The closest correct value would be approximately 39.17%, which is not listed among the choices A, B, C, or D.