An organic compound has the following percentage composition: C=26 70%, H=2 20%, O=71 10% If the vapour density is - Chemistry - Mole Concept and Stoichiometry

Question

An organic compound has the following percentage composition: C=26
70%, H=2 20%, O=71 10% If the vapour density is 45, calculate the
molecular formula of the compound

Aditi Gupta · Accepted Answer

Dear student,

Let take the mass of the compound to be 100 gramMass of carbon = 26
7 gMoles of carbon = 26 712 = 2
225 molMass of hydrogen = 2
2 gMoles of hydrogen = 2 21 = 2
2 molMass of oxygen = 71
1 gMoles of oxygen = 71 116 = 4
44 molTo get the empirical formula divide the least number of moles with all the moles, soC:H:O = 2
22 2 : 2 22 2 : 4 42
2 = 1 : 1 : 2So, the empirical formula is CHO2
Empirical formula mass = 12 + 1 + 16×2 = 45 g/molMolecular mass = 2 × Vapour density = 2× 45 = 90 g/mol  Molecular formula = Molecular massEmpirical Formula mass × Empirical formulaMolecular formula = 9045 × (CHO2)Molecular formula = C2H2O4
Regards

An organic compound has the following percentage composition: C=26.70%, H=2.20%, O=71.10%. If the vapour density is 45, calculate the molecular formula of the compound.