Answer:
The molecular formula is C6H12O6
Explanation:
Step 1: Data given
Mass of the sample fructose = 2.00 grams
Mass of C = 0.80 grams
Molar mass of C = 12.01 g/mol
Mass of O = 1.06 grams
Molar mass of O = 16.0 g/mol
Mass of H = 0.14 grams
Molar mass of H = 1.01 g/mol
Molar mass of the compound = 180 g/mol
Step 2: Calculate moles C
Moles C = 0.80 grams / 12.01 g/mol
Moles C = 0.067 moles
Step 3: Calculate moles O
Moles O = 1.06 grams / 16.0 g/mol
Moles O = 0.066 moles
Step 4: Calculate moles H
Moles H = 0.14 grams / 1.01 g/mol
Moles H = 0.139 moles
Step 5: Calculate the mol ratio
We divide by the smallest amount of moles
C: 0.067 moles : 0.066 moles = 1
O: 0.066 moles / 0.066 moles = 1
H: 0.139 moles / 0.066 moles = 2
For each C atom we have 1 O atom and 2 H atoms
The empirical formula is CH2O
The molar mass of this empirical formula is 30 g/mol
Step 6: Calculate the molecular formula of fructose
We have to multiply the empirical formula of CH2O by n
n = 180 g/mol / 30 g/mol
n = 6
The molecular formula = 6*(CH2O)
The molecular formula is C6H12O6
