Question

Vitamin C contains only carbon, hydrogen, and oxygen. When a 1.00 g was combusted, 1.4991 g of CO2 and 0.4092 g of H2O were obtained. Determine the empirical formula for this vitamin.

Answer 1

The empirical formula for this vitamin : C₃H₄O₃

Further explanation

The empirical formula is the smallest comparison of atoms of compound =mole ratio of the components

The principle of determining empirical formula

• Determine the mass ratio of the constituent elements of the compound.
• Determine the mole ratio by dividing the percentage by the atomic mass

Mass of C in CO₂ :(MW C = 12 g/mol, CO₂=44 g/mol)

`\tt (12)/(44)* 1.4991=0.409~g`

Mass of H in H₂O :(MW H = 1 g/mol, H₂O = 18 g/mol)

`\tt (2.1)/(18)* 0.4092=0.0455~g`

Mass O = Mass sample - (mass C + mass H) :

`\tt 1-(0.409+0.0455)=0.5455~g`

mol ratio C : H : O =

`\tt (0.409)/(12)/ (0.0455)/(1)/ (0.5455)/(16)\\\\0.0341/ 0.0455/ 0.0341\rightarrow 1/ 1.33/ 1=3/ 4/ 3`