When 4-ketopentenoic acid is analyzed by combustion, it is found that a 0.3000g sample produces 0.579 g of CO2 and 0.142 g of H2O. The acid contains only carbon, hydrogen, and oxygen. What is the empirical formula of the acid

C5H6O3

Explanation:

Number of moles of hydrogen = 0.142 * 2 /18  = 0.0158 moles of H

Number of moles of carbon = 0.579 * 1/44 = 0.013 moles of C

Mass of C = 0.013 moles of C * 12 = 0.156 g

Mass of H = 0.0158 moles of H * 1 = 0.0158 g

Mass of oxygen = 0.3000 - (0.156  + 0.0158 )

Mass of oxygen = 0.1282 g

Number of moles of oxygen =  0.1282 g/16 g/mol = 0.008 moles of O

Dividing through by the lowest number of moles

C-0.013/0.008 , H- 0.0158 /0.008 ,  O- 0.008/0.008

1.625,  1.975, 1 (multiply through by 3)

5,          6,      3

The required empirical formula is C5H6O3

the ratio of the conjugate base to the acid required to attain the desired ph.