A 2.87g sample of ascorbic acid (containing C, H, and O only) produces 4.31g CO2 and 1.17g H2O upon combustion. What is the empirical formula of ascorbic acid?

C₃H₄O₃

Explanation:

The empirical formula is the simplest whole-number ratio of atoms present in a molecule. To solve this question we must find the moles of CO2 = Moles of Carbon and moles of H2O = 1/2 moles H.

With the difference in masses of the atoms we can find the mass of ascorbic acid and its moles as follows:

Moles CO2 = Moles C -Molar mass: 44.01g/mol-

4.31g CO2 * (1mol / 44.01g) = 0.0979 moles C * (12.01g/mol) = 1.18g C

Moles H2O -Molar mass: 18.01g/mol

1.17g H2O * (1mol / 18.01g) = 0.0650 moles H2O * (2mol H / 1mol H2O) = 0.130 moles H = 0.13g H

Moles O:

Mass O: 2.87g-0.13g H - 1.18g C = 1.56g O

Moles O:

1.56g O * (1mol/16g) = 0.0975 moles O

Dividing each number of moles of atoms in the moles of Oxygen (The lower number of moles:

O/O = 0.0975 moles O/0.0975 moles O = 1

H/O = 0.130 moles H/ 0.0975 moles O = 1.333

C/O = 0.0979 moles C/ 0.0975 moles O = 1

As empirical formula requires whole-numbers we need to multiply this ratio 3 times:

O = 1*3 = 3

H = 1.333*3 = 4

C = 1*3 = 3

Empirical formula of ascorbic acid is:

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.