1. An unknown acid contains carbon, hydrogen and oxygen. When a 10.46 mg sample

Question

1.     An unknown acid contains carbon, hydrogen and oxygen.  When a 10.46 mg sample was burned in oxygen it gave 26.4 mg of carbon dioxide and 4.63 mg of water.  The molecular mass was determined to be 122 g/mol.  When a 0.1680 g sample of this acid was titrated with 0.1250 M NaOH, the end point was reached after 11.02 mL of base had been added.

a.     What is the empirical formula?

b.     What is the molecular formula?

c.      Is the acid mono-, di- or triprotic?

d.     Knowing this acid is related to acetic acid, give a potential structure of this acid.

e.     Show the mechanism of this acid and the reaction with sodium hydroxide.

An unknown acid contains carbon, hydrogen and oxygen. When a 10.46 mg sample was burned in oxygen it gave 26.4 mg of carbon dioxide and 4.63 mg of water. The molecular mass was determined to be 122 g/mol. When a 0.1680 g sample of this acid was titrated with 0.1250 M NaOH, the end point was reached after 11.02 mL of base had been added. What is the empirical formula? What is the molecular formula? Is the acid mono-, di- or triprotic? Knowing this acid is related to acetic acid, give a potential structure of this acid. Show the mechanism of this acid and the reaction with sodium hydroxide.

Explanation / Answer

.02212*12.01C/44.01CO2=.0061

.0034*2.02H/18.02H2O=.00038

.01046-.0061-.00038=.00398(oxygen)

.0061/12.01/mol= 5.07E-4 mol C

.00038/1.01/mol=3.76E-4 mol H

.00398/16/mol=2.48E-4 mol O

you then divide each mole by the lowest, which is obviously the oxygen one

then you get a empericle formula of c2 h1.5 O1 = c4 h3 O2

the molecular is C8H6O4

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