Unit 9: The Mole Molar Mass Notes

What is molar mass? It is the TOTAL mass of the entire compound. It is the mass of 1 mole of the substance. Every atom of the compound is calculated into the mass. It is expressed in grams/mol (g/mol)

How is molar mass calculated? Use the periodic table to determine the mass of a single mole of a substance. The molar mass comes from the periodic table. AMU=molar mass Unit for molar mass is g/mol Every atom in the compound, has its molar mass added into the overall molar mass of the substance.

Find the molar mass: 1. Copper: 6. Sulfur: 2. Aluminum: 7. Oxygen: 3. Hydrogen: 8. Chlorine: 4. Nitrogen: 9. Potassium: 5. Uranium: 10. Beryllium:

Determining the molar mass of compounds: To add up the mass of EVERY atom in the compound, you must remember. The subscripts represent the number of atoms in a compound O2 = 2 oxygen atoms Yes, If there is a coefficient, you multiply the coefficient by the subscript to calculate the number of atoms, but NOT for the molar mass of a substance. 2CaCl2 = 2 calcium and 4 chlorine atoms The element that the subscript is attached to only applies to that element, unless the subscript is outside parenthesis. PO4 = 1 phosphorus and 4 oxygen (PO4)2 = 2 phosphorus and 8 oxygen 2(PO4)2 = 4 phosphorus and 16 oxygen FOR MOLAR MASS WE ONLY USE SUBSCRIPTS NOT COEFFECIENTS

Determining the molar mass of compounds: Add the molar masses of EVERY atom in the compound together. Find the molar mass of H2O H= 1.00795 = (1) x 2 hydrogen atoms 2g O=15.994= (16) x 1 oxygen atom 16 g Molar mass of H2O 18g/mol *You can use whole numbers instead of decimals but you will need to round!

Number of each type of atom Find the molar mass: Compound Name Compound Formula Number of each type of atom Molar Mass (g/mol) Copper (III) oxide Sodium phosphate Aluminum carbonate Nitrogen Dioxide Lithium Carbonate Sulfur trioxide Calcium sulfide