Answer to Question #135538 in General Chemistry for NeilMar

Question

Alaxan is a pain reliever containing the compound ibuprofen. Analysis of ibuprofen revealed that it contains 75.7% C, 8.80%H and 15.5% O. The molar mass of ibuprofen is 206 g/mol. Determine the molecular formula of ibuprofen.

Answer 1

Elements : C H O

Percentage : 75 8.8 15.5

Atomic Mass: 12 1 16

Moles: 75/12 8.8/1 15.5/16

6.25 8.8 0.97

Ratio: 6.25/0.97 : 8.8/0.97: 0.97/0.97

6.44 : 9.07 : 1

6 : 9 : 1

Empirical formula C₆H₉O₁

Molecular Formula can be calculated as follows:

(C₆H₉O₁)n= 206

97n=206

Therefore, the approximate value of n is 2.

Molecular formula is obtained by substituting n in (C₆H₉O₁)n which gives C₁₂H₁₈O₂