A 25g sample of a compound composed of Carbon, Hydrogen, and Oxygen was combusted. 55grams of Carbon Dioxide and 30 grams of water were collected.

Question

A) What is the empirical formula of the compound?
B) If the compound has a molar mass of 120g what is the molecular formula?

Answer 1

Convert 55 g CO2 to grams C.
Convert 30 g H2O to grams H.
Calculate grams oxygen = 25- g C - g H.

Convert grams to moles.
moles C = g C/atomic mass C.
moles H = g H/atomic mass H.
moles O = g O/atomic mass O.

Now you want to determine the ratio of these elements to each other with the smallest number being 1.00. The easy way to do that is to divide the smallest number by itself (thereby assuring yourself that will be 1.0000), then divide the other two numbers by the same small number. Round to whole numbers. Post your work if you get stuck.

Answer 2

A 25g sample of a compound composed of Carbon, Hydrogen, and Oxygen was combusted. 55grams of Carbon Dioxide and 30 grams of water were collected.
A) What is the empirical formula of the compound?
B) If the compound has a molar mass of 120g what is the molecular formula