Question

Combustion of a 0.9835g sample of a compound containing only carbon, hydrogen, and oxygen produced 1.900g of CO2 and 1.070g of H2O. What is the empirical formula of the compound?

Answer 1

The empirical formula of the compound containing 40.0% C, 6.71% H, and 53.28% O is C2H5O.

Step-by-step explanation:

The empirical formula of a compound can be determined by calculating the molar amounts of each element present in the compound. In this case, we are given the percentages of carbon (40.0%), hydrogen (6.71%), and oxygen (53.28%).

To find the molar amounts, assume a 100g sample of the compound. Thus, there would be 40.0g of carbon, 6.71g of hydrogen, and 53.28g of oxygen.

Using the molar masses of each element, we can convert the masses to moles. Then, we divide the moles by the smallest mole value to obtain the simplest ratio of atoms in the compound. The empirical formula for the compound is C2H5O.

Answer 2

the combustion reaction is CHO + O2 = H20 + CO2
The amount of carbon can be determined by the amount of carbon dioxide.
moles C = 1.90 g CO2 / 44 g/mol CO2 = 0.0432 moles C = 0.5182 g C
The amount of H can be derived from the amount of water
mole H = 1.070 g H2O / 18 g / mol H2O = 0.0594 g H

grams O is 0.9835 - 0.5182 g C - 0.0594 g H = 0.4059 g O.

transforming the determined masses to moles and dividing each to the least among the three, the empirical formula is C2H2O