試題詳解

5. At elevated temperatures, sodium chlorate decomposes to produce sodium chloride and oxygen gas. A 0.8765-g sample of impure sodium chlorate was heated until the production of oxygen gas ceased. The oxygen gas collected over water occupied 57.2 mL at a temperature of 22°C and a pressure of 734 torr. At 22°C the vapor pressure of water is 19.8 torr. The mass percentage of sodium chlorate in the original sample is_____.
(A) 46.5%
(B) 18.0%
(C) 23.3%
(D) 76.7%
(E) 53.5%