Question

Mandelic Acid is an organic acid composed of carbon (63.15%), hydrogen (5.30%), and oxygen (31.55%). Its molar mass is 152.14 g/mol. Determine the empirical and molecular formulas of the acid.

Answer 1

the empirical formula = the molecular formula = C8H8O3

Step-by-step explanation:

Step 1: Data given

Suppose the mass is 100.0 grams

Mandelic acid contains:

Carbon: 63.15 % = 63.15 grams

Hydrogen: 5.30 % = 5.30 grams

Oxygen: 31.55 % = 31.55 grams

Molar mass C = 12.01 g/mol

Molar mass H = 1.01 g/mol

Molar mass O = 16.00 g/mol

Step 2: Calculate moles

Moles = mass / molar mass

Moles C = 63.15 grams / 12.01 g/mol

Moles C = 5.258 moles

Moles H = 5.30 grams / 1.01 g/mol

Moles H = 5.25 moles

Moles O = 31.55 grams / 16.00 g/mol

Moles O = 1.97 moles

Step 3: Calculate mol ratio

We divide by the smallest amount of moles

C: 5.258 moles / 1.97 = 2.67

H: 5.25 / 1.97 = 2.66

O: 1.97 / 1.97

The empirical formula is C8H8O3

The molecular mass of this empirical formula is 152.14 g/mol

This means the empirical formula = the molecular formula = C8H8O3

Answer 2

Empirical formula is C3H3O

Molecular formula C9H9O3

Explanation:

From the question given, we obtained the following data:

Carbon = 63.15%

Hydrogen = 5.30%

Oxygen = 31.55%

We can obtain the empirical and molecular formula by doing the following as illustrated in the attached file. Please see attachment for explanation.