Question

Determine the mass percentage of carbon, C, hydrogen, H, and oxygen, O, in CH40. Refer to the periodic table for the atomic mass of each element.

Answer 1

Ans :

The molar mass of the compound C7H14O is 114.18 g/mol

Atomic mass of C is 12.01 g/mol , H is 1.01 g/mol and of O is 16.00 g/mol

so mass of C in one mol compound = 7 mol x 12.01 g/mol = 84.07 g

mass of H in one mol = 14 mol x 1.01 g/mol = 14.11 g

mass of O in one mol = 1 mol x 16.00 g/mol = 16.00 g

mass percentage = ( mass of element in one mole / molar mass) x 100

so here :

mass percentage C :

= (84.07 g / 114.18 g) x 100

= 73.6 %

Mass percentage H :

= (14.11 g / 114.18 g) x 100

= 12.4 %

Mass percentage O :

= (16.00 g / 114.18 g ) x 100

= 14.0 %