Mass Percent is the percentage of a particular element within a compound.
Concept #1: Understanding the difference between Atomic Mass & Molecular Mass
In order to find the atomic mass of an element you must look it up on your periodic table.
The total mass of a compound is the sum of each elemental atomic mass.
Example #1: What is the total mass of each of the following compounds?
a. N2O5 b. C12H22O11 c. (NH4)3PO4
Concept #2: Understanding Mass Percent
Example #2: What is the percentage of carbon in sodium hydrogen carbonate, NaHCO3?
In order to calculate the molecular mass or weight of a compound you must look up the atomic mass or weight of each element.
Example #3: A sample of toothpaste contains tin (II), SnF2. Analysis of a 5.25 g sample contains 8.77 x 10-3 g of F. What is the percentage of tin (II) fluoride in the sample?
To go from the atomic mass of an element to the molecular mass of a compound you must use stoichiometric relationships.
Practice: Hemoglobin contains 0.33% iron and has a molecular weight of 68 kg. How many iron atoms are in each molecule of hemoglobin?