# MOLAR MASS The molar mass is the mass, in grams, of one mole (6.02  1023 particles) of an element (ion), a covalent molecule or a formula unit. molar.

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MOLAR MASS The molar mass is the mass, in grams, of one mole (6.02  1023 particles) of an element (ion), a covalent molecule or a formula unit. molar mass (MM) gram atomic mass (gam) molecular weight (MW) gram molecular mass (gmm) formula mass (FM) gram formula mass (gfm) formula weight (FW)

MASS of one MOLE Gram atomic mass (gam): the atomic mass (the mass in one mole of a substance) of an element expressed in grams. Gram molecular mass (gmm): the atomic mass of one mole of a molecular compound. Gram formula mass (gfm): the sum of the atomic masses of the atoms that are in the formula of a compound.

gam, gfm, gmm examples: Problem: Give the gram atomic mass of hydrogen. Solution: H = 1H = 1(1.01) = 1.01 g/mol Problem: Give the gram molecular mass of hydrogen. Solution: H2 = 2H = 2(1.01) = 2.02 g/mol Problem: Find the gram formula mass for H2SO4. Solution: H2SO4 = 2H + 1S + 4O = 2(1.01) (16.00) = g/mol

Molar Mass … a.k.a. Molecular Weight (MW)
molar mass = mass of 1 mole of substance Molar mass can be determined by adding up the atomic masses from the periodic table (atomic mass goes to 2 decimal places).

MW Example 1: = 1C + 4H = 12.01 + 4(1.01) = 16.05 g CH4/mol CH4
Find the MW of CH4. = 1C + 4H = (1.01) = g CH4/mol CH4

MW Example 2: =Mg + 2O + 2H =24.31 + 2(16.00) + 2(1.01)
Find the MW of Mg(OH)2. =Mg + 2O + 2H = (16.00) + 2(1.01) =58.33 g Mg(OH)2 /mol Mg(OH)2

MW Example 3: Find the MW of MgSO4∙7H2O. =Mg + S + 4O + 7(H2O)
= (16.00) + 7( ) = g MgSO4∙7H2O /mol MgSO4∙7H2O

Calculations: Use Mole Map to help calculate

Mole Mass Calculations
1 mole = molar mass (MW) in grams Mass MOLE

Mass Example 1: How many grams are in 7.20 moles of dinitrogen trioxide? dinitrogen trioxide = N2O3 MW of N2O3 = 2N + 3O = 2(14.01) + 3(16.00) = g/mol 1 mole = g N2O3

MW of Fe2O3 = 2Fe + 3O = 2(55.85) + 3(16.00) = 159.70 g/mol
Mass Example 2: Find the number of moles in 92.2 g of iron(III) oxide. iron(III) oxide = Fe2O3 MW of Fe2O3 = 2Fe + 3O = 2(55.85) + 3(16.00) = g/mol 1 mole = g Fe2O3

Make sure you write out all work and include all units!!
Practice Worksheet Do #1-10 on Mole and Mass WS Make sure you write out all work and include all units!!

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