Question

1. Show how to convert grams to moles of each element

2. Show how to divide by the smallest number of moles
3. Show how to find the empirical formula
You have 245.1 grams of C
You have 41.23 grams of H
You have 81.64 grams of O

Answer 1

1.To convert grams to moles, divide the mass of each element by its molar mass:

C: 245.1 g / 12.01 g/mol = 20.41 mol

H: 41.23 g / 1.01 g/mol = 40.83 mol

O: 81.64 g / 16.00 g/mol = 5.10 mol

2.Divide each number of moles by the smallest number of moles:

C: 20.41 mol / 5.10 mol = 4.00

H: 40.83 mol / 5.10 mol = 8.00

O: 5.10 mol / 5.10 mol = 1.00

3.The empirical formula is the simplest whole-number ratio of atoms in a compound. The subscripts in the empirical formula are the numbers obtained in step 2:

C: 4

H: 8

O: 1

Therefore, the empirical formula for the compound is C4H8O.