What is the formula mass of ethyl alcohol, #C_2H_5OH#?

1 Answer
Jan 26, 2016


46.08 gram per mole (g/mol)


In order to arrive with this answer, we should know the atomic weight of the elements present in the compound—in this case, the elements are Carbon, Hydrogen, and Oxygen.

The atomic weight for these elements are the following (expressed to the nearest hundredth):

Carbon = 12.01 g/mol
Oxygen = 16.00 g/mol
Hydrogen = 1.01 g/mol

Now, let's count the total number of each element (expressed in moles) bonded in the compound:

Carbon = 2
Oxygen = 1
Hydrogen = 6

To calculate for the formula, we should multiply the atomic weights of each element to the corresponding number of moles in the the compound.

Carbon: 12.01 x 2 = 24.02
Oxygen: 16.00 x 1 = 16.00
Hydrogen: 1.01 x 6 = 6.06

The sum is equal to 48.08 grams per mole; wherein grams per mole can also be denoted as atomic mass unit