Empirical and Molecular Formulas

This video tutorial explains how to determine the empirical formula of a compound from its percent composition and how to find the molecular formula if the molar mass is provided. It includes step-by-step examples, starting with converting percent composition to grams, then to moles, and finally deriving the empirical formula. The tutorial also covers calculating the molecular formula by comparing the molar mass of the empirical formula with the given molar mass of the compound.

What is the first step in finding the empirical formula from percent composition?

• Convert moles to grams

• Convert grams to liters

• Convert grams to percent

• Convert percent to grams

How do you determine the smallest number of moles when calculating the empirical formula?

• By comparing the calculated moles

• By comparing the molar masses

• By comparing the atomic numbers

• By comparing the percent composition

What is the empirical formula for a compound with 52.14% carbon, 13.13% hydrogen, and 34.73% oxygen?

• C3H8O

• C2H6O

• CH3O

• C2H6

What is the next step after finding the empirical formula to determine the molecular formula?

• Find the boiling point of the compound

• Find the density of the compound

• Find the atomic number of each element

• Find the molar mass of the empirical formula

How do you calculate the molecular formula from the empirical formula?

• Subtract the molar mass of the empirical formula from the compound's molar mass

• Multiply the empirical formula by the atomic number

• Divide the molar mass of the compound by the molar mass of the empirical formula

• Add the atomic masses of the elements

What is the empirical formula for a compound with 20.32 grams of carbon, 5.12 grams of hydrogen, and 7.9 grams of nitrogen?

• CH4N

• C2H5N

• C4H10N

• C3H9N

What is the molar mass of the empirical formula C3H9N?

• 60.112 g/mol

• 58.112 g/mol

• 59.112 g/mol

• 57.112 g/mol

How do you find the molecular formula if the molar mass of the compound is 236.448 g/mol and the empirical formula is C3H9N?

• Multiply the empirical formula by 2

• Multiply the empirical formula by 3

• Multiply the empirical formula by 4

• Multiply the empirical formula by 5

What is the molecular formula for a compound with an empirical formula of C3H9N and a molar mass of 236.448 g/mol?

• C6H18N2

• C9H27N3

• C12H36N4

• C15H45N5

What is the final step in determining the molecular formula from the empirical formula?

• Add the atomic masses of the elements

• Subtract the atomic masses of the elements

• Divide the subscripts of the empirical formula by the calculated factor

• Multiply the subscripts of the empirical formula by the calculated factor