The taste of sour milk is lactic acid. What is the molecular formula for lactic acid if the percent composition is 40.00% C, 6.71% H, 53.29% O, and the approximate molar mass is 90 g/mol?

Question

Chemistry

Janessa Levine

1 February, 20:35

The taste of sour milk is lactic acid. What is the molecular formula for lactic acid if the percent composition is 40.00% C, 6.71% H, 53.29% O, and the approximate molar mass is 90 g/mol?

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Answers (1)

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Brenden Kelley · Answer 1

C3H6O3

Explanation:

To find the emperical of the compound, you divide the percentage composition of each element by it's molar mass (C=12, H=1, O=16).

For C, 40/12=3.33. For H, 6.71/1=6.71

For O, 53.19/16=3.33.

Then divide everything by the smallest value which is 3.33

For C, 3.33/3.33=1. For H, 6.71/3.33=~2.

For O, 3.33/3.33=1.

Emperical formula=CH2O

Molecular formula = (CH2O) n=90

(12+2*1+16) n=90

30n=90, n=3

molecular formula = (CH2O) 3

molecular formula of lactic acid=C3H6O3.