In: Chemistry
A 4.043 sample of a compound containing only carbon, hydrogen, and oxygen is burned in an excess of dioxygen, producing 9.191 g CO2 and 3.762 g H2O. What percent by mass of oxygen is contained in the original sample? show your work and explain.
moles of CO2 = mass / molar mass
= 9.191 / 44
= 0.2089
mass of C = 0.2089 x 12 = 2.507 g
moles of H2O = 3.762 / 18 = 0.209
moles of H = 2 x 0.209 = 0.418
mass of H = 0.418
mass of O = total mass - (mass of C + mass of H )
= 4.043 - (2.507 + 0.418)
= 1.118 g
percent by mass of oxygen = ( mass of O / total mass ) x 100
= (1.118 / 4.043 ) x 100
= 27.65 %