Question

A compound is 80.0% carbon and 20.0% hydrogen by mass. Assume you have a 100.-g sample of this compound.

Part A
How many grams of each element are in this sample?
Enter the number of grams of carbon followed by the number of grams of hydrogen, separated by a comma (e.g., 30.0,70.0).

Part B
How many moles of each element are in this sample?
Enter the number of moles of carbon followed by the number of moles of hydrogen, separated by a comma.

Part C
Based on the mole ratio you determined in Part C, what is the empirical formula of this compound?

The molar mass of the compound was found to be 30.069 g/mol. What is the molecular formula?

Answer 1

The compound contains 80.0 g of carbon and 20.0 g of hydrogen. The empirical formula is CH₃ and the molecular formula is C₂H₆.

Step-by-step explanation:

To determine the grams of each element in a compound, we assume a 100 g sample. From the given percentages, we have 80.0 g of carbon and 20.0 g of hydrogen.

To find the moles of each element, we convert the grams to moles using the molar mass of carbon (12.01 g/mol) and hydrogen (1.01 g/mol). This gives us 6.66 moles of carbon and 19.80 moles of hydrogen.

The mole ratio of carbon to hydrogen is 1:3, so the empirical formula of the compound is CH₃.

To find the molecular formula, we need the molar mass. Given that the molar mass is 30.069 g/mol, we divide it by the empirical mass of CH₃ (14.03 g/mol) to get a molecular formula of C₂H₆.