Answer:
The empirical formula is C4H8O
Explanation:
Step 1: Data given
Valproic acid is composed of C, H, and O
Mass of the sample = 0.165 grams
Mass of water = 0.166 grams
Mass of CO2 = 0.403 grams
Molar mass of water ( H2O) = 18.02 g/mol
Molar mass of CO2 = 44.01 g/mol
Atomic mass of C = 12.01 g/mol
Atomic mass of O = 16.0 g/mol
Atomic mass H = 1.01 g/mol (H2 = 2.02 g/mol)
Step 2: The equation
CxHyOz + O2 → CO2 + H2O
Step 3: Calculate the number of carbon in the sample
The carbon comes from CO2
Mass C = (12.01 g/mol/44.01 g/mol) * 0.403 grams
Mass C = 0.110 grams
Step 4: Calculate mass of hydrogen in the sample
The hydrogen comes from H2O
Mass H = (2.02/18.02) * 0.166 grams
MAss H = 0.0186 grams
Step 5: Calculate mass of O
The mass of O in the sample = Mass of sample - mass of H - mass of C
The mass of O = 0.165 grams - 0.110 grams - 0.0186 grams
The mass of O = 0.0364 grams
Step 6: Calculate moles
Moles C = 0.110 grams / 12.01 g/mol = 0.00916 moles
Moles H = 0.0186 / 1.01 = 0.0184 moles
Moles O = 0.0364/16.0 = 0.00228 moles
Step 7: Calculate empirical formula
We divide by the smallest amount of moles
C: 0.00916/ 0.00228 = 4
H: 0.0184/0.00228 = 8
O: 0.00228/0.00228 = 1
The empirical formula is C4H8O
