Transcript Empirical Formulas

Empirical Formulas
• Gives the lowest whole-number ratio of the
elements in a compound.
• Example: Hydrogen Peroxide (H2O2)
• Empirical Formula- HO
Steps
• Determine the number of moles for each
element.
• Divide all elements by the smallest number
of moles.
• You may need to multiply in order to get all
elements in whole numbers.
Determining Empirical Formulas
• A compound is analyzed and found to
contain 25.9% nitrogen and 74.1% oxygen.
What is the empirical formula?
• Calculate the empirical formulas:
• 94.1% O, 5.9% H
• 67.6% Hg, 10.8% S, 21.6% O
Molecular Formulas
• Can be a multiple of the empirical formula.
• Example: H2O2 can be divided by 2 to become HO.
Finding Molecular
Formula of a Compound
• Calculate the molecular formula of a compound
whose molar mass is 60.0 g/mole and the empirical
formula is CH4N.
• CH4N has a empirical formula mass of 30.0
g/mole.
• So 60.0 g/ 30.0 g = 2
• Molecular formula = C2H8N2