Question

Riboflavin is one of the B vitamins It is also known as B6 and is made up of carbon, hydrogen, nitrogen and oxygen atoms. When 10.0 g of vitamin B6 is burned in oxygen, 19.88 g of CO2 and 4.79 g of H2O are obtained. Another experiment shows that vitamin B6 is made up of 14.89% of N. What is the simplest formula for vitamin B6

Answer 1

Answer:

C₁₇H₂₀N₄O₆

Explanation:

First, we need to determine the percentage of the atoms in the molecule. Then, assuming a basis of 100 we must convert the mass of each atom to moles. Simplest formula is the simplest ratio of atoms presents in the molecule:

%C:

19.88g CO2 * (12.01g/mol C / 44.01g/mol CO2) = 5.425g C

5.425g C / 10.0g * 100 = 54.25% C

%H:

4.79g H2O * (2*1.01g/mol / 18.015g/mol) = 0.537g H

0.537g H / 10.0g * 100 = 5.37%

%N:

14.89%

%O:

100 - 14.89% - 54.25% - 5.37% = 25.49%

Moles of each atom in a basis of 100g:

C: 54.25g * (1mol / 12.01g) = 4.517moles

H: 5.37g * (1mol / 1.01g) = 5.317 moles

N: 14.89g * (1mol / 14.01g) = 1.063 moles

O: 25.49g * (1mol / 16g) = 1.593 moles

Dividing each amount of moles in the lower number of moles (moles N):

C = 4.517mol / 1.063mol = 4.25

H = 5.317mol / 1.063mol = 5

N = 1.063mol / 1.063mol = 1

O = 1.593mol / 1.063mol = 1.5

This ratio multiplied 4 times to obtain whole-numbers:

C = 4.25*4 = 17

H = 5*4 = 20

N = 1*4 = 4

O = 1.5*4 = 6

The simplest formula for vitamin B6 is:

C₁₇H₂₀N₄O₆