Question

Caproic acid, responsible for the odor of dirty socks, is composed of C, H, and O atoms. Combustion of a 0.225-g sample of this compound produces 0.512 g CO2 and 0.209 g H2O. (a)What is the empirical formula of caproic acid? (b) Caproic acid has a molar mass of 116 g/mol. What is its molecular formula?

Answer 1

Answer:   Empirical formula = C3H6O

C6H1202---Molecular formula

Explanation:

we first find the masses of C, H  and O contained in the sample

mass of carbon

Mass of CO2 = 0.512g

molar mass of carbon =  12g/mol

Molar mass CO2 =  12+ (16X2)=44g/mol

Mass C = 12/44x 0.512 = 0.1396g  of carbon

Mass Hydrogen  

mass of H2O= 0.209g

Molar mass H2O = 18g/mol

Molar mass Hydrogen  = 1.0079g  x 2 = 2.0158g since  Hydrogen gas is diatomic

Mass H = 2.0158/18 X 0.209 = 0.0234g Hydrogen

Mass of Oxygen in the sample  =  overall mass of Sample - mass of hydrogen and oxgen=

0.225 - ( 0.1396 + 0.0234) = 0.062g Oxygen

A) T o find Empirical formula

1ST STEP-- Divide through by each  relative  atomic mass:

C = 0.1396/12 = 0.01163

H = 0.0234/1.0079 = 0.0232

O = 0.0619/16 = 0.00387

2nd step  Divide  by smallest answer

C = 0.01163/0.00387 = 2.0998 = 3

H = 0.0232/0.00387 = 5.99 = 6

O = 0.00387/0.00387=1

Empirical formula = C3H6O

B)To find molecular formula

Given that  molar mass of caproic acid as 116g,

we will use our empirical formulae to find molecular formulae with the equation

(C3H6O)n= 116g/mol

12x3 + 1x6 + 1 x16= 58g/mol

58n= 116g/mol

n = 116/58= 2  

= (C3H6O)2= C(3X2) H(6X2) O(1X2)

C6H1202--- MOLECULAR FORMULA