# Percent Composition by Mass of Oxygen in Potassium Chlorate

359 Words1 Page

% Composition By Mass of Oxygen in Potassium Chlorate Objective: The purpose of this lab was to calculate the percent composition by mass of oxygen in potassium chlorate. Procedure: 1.The mass of the crucible and the cover was measured. 2.KClO3 was added to the crucible. 3.The mass of the crucible, cover and KClO3 was measured. 4.MnO2 was added in the crucible. 5.The mass of the crucible, cover, KClO3 and MnO2 was measured. 6.The Bunsen Burner was lit. 7.The covered crucible was placed over the flame of the Bunsen Burner using a ring stand. 8.The flame was waved under the crucible for 2 minutes. 9.The flame was placed directly under the crucible until hot and glowing. 10.The Bunsen Burner was turned off. 11.The mass of the covered crucible was measured once cooled. Theory: Mass of 2KClO3 - Mass of 2KCl = Mass of 3O2 Mass of KClO3 = Mass of crucible, cover and KClO3 (Step # 3) - Mass of crucible and cover (Step # 1) Mass of O = Mass of crucible, cover, KClO3 and MnO2 after heating (Step # 11) - Mass of crucible, cover, KClO3 and MnO2 before heating (Step # 5) % composition= __Mass of O_ x 100 Mass of KClO3 Data: Mass of crucible and cover ~ 26.40g Mass of crucible, cover and KClO3 ~ 28.59g Mass of crucible, cover, KClO3 and MnO2 ~ 29.55g Mass of crucible, cover, KClO3 and MnO2 after heating ~ 28.60g Calculation: Mass of KClO3: 28.59g - 26.40g = 2.19g Mass of O2: 29.55g - 28.60g = 0.95g % Composition by mass: _(29.55g-28.60g) x 100 = 43.40% (28.59g-26.40g) Theoretical: __(3x16g)____ x 100 = 39.2% (39.1g + 35.5g + (3x16g) .392 x (28.59g - 26.40g) = .859g Discussion: The % composition by mass of oxygen in Potassium Chlorate was found to be 43.4%. The error analysis ~ _ç.