Mandelic acid is an organic acid composed of carbon (63.15%), hydrogen (5.30%), and oxygen (31.55%). Its molar mass is 152.15 g/mol. Determine the empirical and molecular formulas of the acid.

The answer to your question is empirical formula  C₂.₆H₂.₆O₁

                                                    molecular formula  C₈H₈O₃    

Explanation:

Data

Carbon   63.15%

Hydrogen  5.30%

Oxygen  31.55 %

Molar mass = 152.15 g

Process

1.- Express the percents as grams

Carbon   63.15g

Hydrogen  5.30g

Oxygen  31.55 g

2.- Calculate the moles of these elements

Carbon               12 g 1 mol

                           63.15 g  x

                           x = (63.15 x 1) / 12

                           x = 5.2625 moles

Hydrogen             1 g 1 mol

                           5.3 g  x

                           x = (5.3 x 1)/1

                           x = 5.3 moles

Oxygen                 16 g 1 mol

                             31.55 g  x

                              x = (31.55 x 1)/16

                              x = 1.97 moles

2.- Divide by the lowest number of moles

Carbon          5.2625/1.97 = 2.6  

Hydrogen      5.3/1.97 = 2.6        

Oxygen          1.97/197 = 1              

3.- Write the empirical formula

                          C₂.₆H₂.₆O₁

4.- Write the molecular formula

Molar mass of empirical formula = (12 x8) + (1 x 8) + (16 x 3) = 152

                          152.15/149.8 = 3

Multiply the empirical formula by 3

                          C₈H₈O₃