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Ch.6 Chemical Reactions & QuantitiesWorksheetSee all chapters
All Chapters
Ch.1 Matter and Measurements
Ch.2 Atoms and the Periodic Table
Ch.3 Ionic Compounds
Ch.4 Molecular Compounds
Ch.5 Classification & Balancing of Chemical Reactions
Ch.6 Chemical Reactions & Quantities
Ch.7 Energy, Rate and Equilibrium
Ch.8 Gases, Liquids and Solids
Ch.9 Solutions
Ch.10 Acids and Bases
Ch.11 Nuclear Chemistry
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Empirical Formula
Molecular Formula
Calculating Molar Mass
Mole Concept
Mass Percent
Limiting Reagent
Percent Yield

The empirical formula gives the relative number of atoms. 

Empirical Formula

Concept #1: Empirical Formula

Example #1: Determine the empirical formula of a compound that is 68.40% chromium and 31.60% oxygen.

Practice: A compound that contains only carbon, hydrogen, and oxygen is composed of 48.64% C and 43.2% O by mass. What is the empirical formula of this compound?

Practice: Elemental analysis of a sample of an ionic compound showed 2.82 g of Na, 4.35 g of Cl, and 7.83 g of O. What is the empirical formula of the compound?

Practice: A compound composed of carbon, hydrogen, and chlorine contains 4.19 x 1023 hydrogen atoms. If 9.00 g of the compound also contains 55.0% chlorine by mass, what is the empirical formula?