Potassium Chlorate
The Composition of Potassium Chlorate
Objectives
The objectives of this laboratory are: a) To experimentally determine the mass percent of oxygen in the compound potassium chlorate (KClO3) via the thermal decomposition of a sample of potassium chlorate. b) To qualitatively demonstrate that the residue resulting from the decomposition of potassium chlorate is potassium chloride.
Background
All compounds consist of elements chemically combined in fixed proportions – they obey the Law of Constant Composition. One way to express the proportion each of element in a compound is as a percentage by mass, or mass percent. In Part A of this lab, a sample of potassium chlorate will be experimentally analyzed in order to determine the mass percent of elemental oxygen present in it. To do this, the potassium chlorate must be heated to temperatures greater 400 °C, causing it to thermally decompose into potassium chloride and free oxygen: heat 2 KClO3 (s)
Potassium Chlorate
→
2 KCl (s)
Potassium Chloride
+
3 O2 (g)
Oxygen
Students will perform a quantitative analysis of the reactants and products of this reaction, measuring the initial mass of solid potassium chlorate used (before heating), and the mass of the solid potassium chloride product, or residue, remaining after heating. Applying the Law of Mass Conservation, the difference in these measured masses is the mass of oxygen released (from the original potassium chlorate sample). From this data, the experimental mass percent of oxygen in potassium chlorate will be determined: Mass of Oxygen Released x 100 Mass of Potassium Chlorate Used
Mass Percent of Oxygen (experimental) =
Mass percentages of elements in compounds can also be theoretically calculated using molar masses, along with the known chemical formula of the compound. Thus, the theoretical mass percent of oxygen in potassium chlorate would be calculated using the expression: 3 (Molar Mass of O) Molar Mass of KClO3
Mass Percent of
Objectives
The objectives of this laboratory are: a) To experimentally determine the mass percent of oxygen in the compound potassium chlorate (KClO3) via the thermal decomposition of a sample of potassium chlorate. b) To qualitatively demonstrate that the residue resulting from the decomposition of potassium chlorate is potassium chloride.
Background
All compounds consist of elements chemically combined in fixed proportions – they obey the Law of Constant Composition. One way to express the proportion each of element in a compound is as a percentage by mass, or mass percent. In Part A of this lab, a sample of potassium chlorate will be experimentally analyzed in order to determine the mass percent of elemental oxygen present in it. To do this, the potassium chlorate must be heated to temperatures greater 400 °C, causing it to thermally decompose into potassium chloride and free oxygen: heat 2 KClO3 (s)
Potassium Chlorate
→
2 KCl (s)
Potassium Chloride
+
3 O2 (g)
Oxygen
Students will perform a quantitative analysis of the reactants and products of this reaction, measuring the initial mass of solid potassium chlorate used (before heating), and the mass of the solid potassium chloride product, or residue, remaining after heating. Applying the Law of Mass Conservation, the difference in these measured masses is the mass of oxygen released (from the original potassium chlorate sample). From this data, the experimental mass percent of oxygen in potassium chlorate will be determined: Mass of Oxygen Released x 100 Mass of Potassium Chlorate Used
Mass Percent of Oxygen (experimental) =
Mass percentages of elements in compounds can also be theoretically calculated using molar masses, along with the known chemical formula of the compound. Thus, the theoretical mass percent of oxygen in potassium chlorate would be calculated using the expression: 3 (Molar Mass of O) Molar Mass of KClO3
Mass Percent of