Problem: A 2.52-g sample of a compound containing only carbon, hydrogen, nitrogen, oxygen, and sulfur was burned in excess oxygen to yield 4.23 g of CO2 and 1.01 g of H2O. Another sample of the same compound, of mass 4.14 g, yielded 2.11 g of SO3. A third sample, of mass 5.66 g, was burned under different conditions to yield 2.27 g of HNO3 as the only nitrogen-containing product.Calculate the empirical formula of the compound.

FREE Expert Solution


mass percent = mass componentmass sample

Step 1. Calculate mass % C

4.32 g CO2 ×1   mol CO2 44.01  g CO2  × 1   mol C1   mol CO2 ×12.01 g C1 mol C= 1.18 g C

% C= 1.18 g2.52 g  × 100

% C = 46.83


Step 2. Calculate mass % H


1.01 g H2O×1  mol H2O18.02  g H2O × 2   mol H1   mol H2O×1.01 g H1 mol H= 0.11 g H

% H= 0.11 g2.52 g  × 100

% H = 4.49 %


Step 3. Calculate mass % S

 2.11  g SO3×1  mol SO380.07   g SO3 × 1   mol S1  mol SO3×32.07 g S1 mol S= 0.845 g S

% S= 0.845 g4.14 g  × 100

% S = 20.41 %


Step 4. Calculate mass % N


 2.27  g HNO3×1  mol HNO363.02  g HNO3 × 1   mol N1 mol HNO3×14.01 g N1 mol N= 0.505 g N

% N= 0.505 g5.66 g  × 100

% N = 8.92 %


Step 5. Calculate mass % O

This will just be what is left of 100 %.

% O = 100% - %C -% H - %S - %N% O = 100% - 46.86 %-4.49 % - 20.41% - 8.92%% O = 19.35 %


Step 6. Calculate the moles of each

Assume 100 g → the mass percent will be equal to the mass. 

Then calculate moles based on molar mass. 

mol C = 46.83 g C12.01  g /mol C = 3.90 mol Cmol H = 4.49 g H1.01  g /mol H = 4.45 mol Hmol S = 20.41 g S32.07  g /mol S = 0.636 mol Smol N = 8.92 g N14.01  g /mol N = 0.636 mol Nmol O = 19.35 g O16.00  g /mol O = 1.21 mol O

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Problem Details

A 2.52-g sample of a compound containing only carbon, hydrogen, nitrogen, oxygen, and sulfur was burned in excess oxygen to yield 4.23 g of CO2 and 1.01 g of H2O. Another sample of the same compound, of mass 4.14 g, yielded 2.11 g of SO3. A third sample, of mass 5.66 g, was burned under different conditions to yield 2.27 g of HNO3 as the only nitrogen-containing product.

Calculate the empirical formula of the compound.

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