Posted by Fred on .
At elevated temperatures, sodium chlorate decomposes to produce sodium chloride and oxygen gas. A 0.8915-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. Calculate the mass percent of NaClO3 in the original sample. (At 22°C the vapor pressure of water is 19.8 torr.)
2NaClO3 ==> 2NaCl + 3O2
Solve for mols O2.
P gas (O2 + H2O) = 734 mm
PH2O = 19.8
PO2 = 734-19.8 = 714.2 mm
Use PV = nRT and solve for n
Convert to mols NaClO3 using the coefficients in the balanced equation.
mols O2 x (2 mols NaClO3/3 mols O2) = ?
Convert mols NaClO3 to grams. g = mols x molar mass.
%NaClO3 = (g NaClO3/mass sample)*100 = ?