Answer:
The molecular formula is C8H8O2
Explanation:
Step 1: Data given
Mass of compound X = 5.50 grams
Mass of CO2 = 14.24 grams
Molar mass of CO2 = 44.01 g/mol
Mass of H2O = 2.91 grams
Molar mass H2O = 18.02 g/mol
Molar mass C = 12.01 g/mol
Molar mass O = 16.0 g/mol
Molar mass H = 1.01 g/mol
Molar mass of the compound = 136 g/mol
Step 2: Calculate moles CO2
Moles CO2 = 14.24 grams / 44.01 g/mol
Moles CO2 = 0.324 moles
Step 3: Calculate moles C
For 1 mol cO2 we have 1 mol C
For 0.324 moles CO2 we have 0.324 moles C
Step 4: Calculate mass C
Mass C = 0.324 moles * 12.01 g/mol
Mass C = 3.89 grams
Step 5: Calculate moles H2O
Moles H2O = 2.91 grams / 18.02 g/mol
Moles H2O = 0.161 moles
Step 6: Calculate moles H
For 1 mol H2O we have 2 moles H
For 0.161 moles H2O we have 2*0.161 = 0.322 moles H
Step 7: Calculate mass H
Mass H = 0.322 moles * 1.01 g/mol
Mass H = 0.325 grams
Step 8: Calculate mass O
Mass O = 5.50 grams - 3.89 grams - 0.325 grams
MAss O = 1.285 grams
Step 9: Calculate moles O
Moles O = 1.285 grams / 16.0 g/mol
Moles O = 0.0803 moles
Step 10: Calculate mol ratio
We divide by the smallest amount of moles
C: 0.324 moles / 0.0803 moles = 4
H: 0.322 moles / 0.0803 moles = 4
O: 0.0803 moles / 0.0803 moles = 1
The empirical formula is C4H4O
The molar mass of this empirical formula is 68 g/mol
Step 11: Calculate the molecular formula
We have to multiply the empirical formula by n
n = 136 g/mol / 68 g/mol
n = 2
We have to multiply the empirical formula by 2
Molecular formula = 2*(C4H4O) = C8H8O2
The molecular formula is C8H8O2
