Understanding Molecular and Empirical Formulas

What does the molecular formula of a compound indicate?

• The lowest whole number ratio of atoms

• The arrangement of atoms in 3D space

• The number of atoms of each element in a molecule

• The molar mass of the compound

How is the empirical formula different from the molecular formula?

• It shows the 3D structure of the molecule

• It is always a multiple of the molecular formula

• It gives the lowest whole number ratio of atoms

• It provides the exact number of atoms in a molecule

What is the molecular formula of acetic acid if its empirical formula is CH2O?

• C6H12O6

• CH2O

• C2H4O2

• C3H6O3

Which step is NOT part of finding the molecular formula from the empirical formula?

• Divide the molar mass by the empirical formula mass

• Determine the 3D structure of the compound

• Calculate the empirical formula mass

• Multiply the empirical formula by the result

What is the molecular formula of glucose if its empirical formula is CH2O and the molar mass is 180 g/mol?

• C6H12O6

• CH2O

• C2H4O2

• C12H24O12

In the example of hydrogen peroxide, what is the empirical formula derived from the percent composition?

• O2H2

• H2O2

• HO

• H2O

How many empirical formula units are in one molecule of hydrogen peroxide?

• 4

• 3

• 2

• 1

What is the empirical formula of butane if its molecular formula is C4H10?

• C2H4

• CH3

• C2H5

• C4H10

What is the greatest common divisor used to simplify the molecular formula of butane?

• 5

• 1

• 3

• 2

Which of the following is true about empirical formulas?

• They are always identical to molecular formulas

• They are always a multiple of molecular formulas

• They may or may not be the same as molecular formulas

• They provide the 3D structure of the compound