Formula Mass of Formula Mass of CompoundsCompounds

Molar mass of an elementMolar mass of an element

Molar mass = mass in grams of 1 Molar mass = mass in grams of 1 mole of any pure substance.mole of any pure substance.

Molar mass of an element Molar mass of an element numerically equal to atomic mass but numerically equal to atomic mass but units change to grams per mole.units change to grams per mole.

Molar mass of elementsMolar mass of elements

Na has an atomic mass of 22.990 Na has an atomic mass of 22.990 amuamu so its molar mass = 22.990 so its molar mass = 22.990 gramsgrams

K has an atomic mass of 39.098 K has an atomic mass of 39.098 amuamu so its molar mass = 39.098 so its molar mass = 39.098 gramsgrams..

Ca has an atomic mass of 40.078 Ca has an atomic mass of 40.078 amuamu so its molar mass = 40.078 so its molar mass = 40.078 gramsgrams..

Molar massMolar mass

Also called formula mass.Also called formula mass.

Or gram formula mass.Or gram formula mass.

Molar Mass of Molar Mass of CompoundsCompounds

= sum of the masses of the atoms in = sum of the masses of the atoms in the formula.the formula.

Round atomic masses to the nearest Round atomic masses to the nearest tenth.tenth.

Ex: HEx: H22OO

– 2 X H = 2 X 1.0 = 2.02 X H = 2 X 1.0 = 2.0– 1 X O = 1 X 16.0 = 16.01 X O = 1 X 16.0 = 16.0

Sum = 2.0 + 16.0 = 18.0Sum = 2.0 + 16.0 = 18.0

Molar Mass of CompoundsMolar Mass of Compounds

Try CHTry CH44

1 X C = 1 X 12.0 = 12.01 X C = 1 X 12.0 = 12.0

4 X H = 4 X 1.0 = 4.04 X H = 4 X 1.0 = 4.0

Sum = 4.0 + 12.0 = 16.0Sum = 4.0 + 12.0 = 16.0

Molar Mass of CompoundsMolar Mass of Compounds

Try COTry CO22

1 X C = 1 X 12.0 = 12.01 X C = 1 X 12.0 = 12.0

2 X O = 2 X 16.0 = 32.02 X O = 2 X 16.0 = 32.0

Sum = 12.0 + 32.0 = 44.0Sum = 12.0 + 32.0 = 44.0

Molar Mass of CompoundsMolar Mass of Compounds

Try NaClTry NaCl

1 X Na = 1 X 23.0 = 23.01 X Na = 1 X 23.0 = 23.0

1 X Cl = 1 X 35.5 = 35.51 X Cl = 1 X 35.5 = 35.5

Sum = 23.0 + 35.5 = 58.5Sum = 23.0 + 35.5 = 58.5

Molar Mass of CompoundsMolar Mass of Compounds

Try CTry C66HH1212OO66

6 X C = 6 X 12.0 = 72.06 X C = 6 X 12.0 = 72.0

12 X H = 12 X 1.0 = 12.012 X H = 12 X 1.0 = 12.0

6 X O = 6 X 16.0 = 96.06 X O = 6 X 16.0 = 96.0

Sum = 72.0 + 12.0 + 96.0 = Sum = 72.0 + 12.0 + 96.0 = 180.0180.0

Molar Mass of CompoundsMolar Mass of Compounds

Try Cu(OH)Try Cu(OH)22

1 X Cu = 1 X 63.5 = 63.51 X Cu = 1 X 63.5 = 63.5

2 X O = 2 X 16.0 = 32.02 X O = 2 X 16.0 = 32.0

2 X H = 2 X 1.0 = 2.02 X H = 2 X 1.0 = 2.0

Sum = 63.5 + 32.0 +2.0 = Sum = 63.5 + 32.0 +2.0 = 97.597.5

Molar Mass of CompoundsMolar Mass of Compounds

Try Al(NOTry Al(NO33))33

1 X Al = 1 X 27.0 = 27.01 X Al = 1 X 27.0 = 27.0

3 X N = 3 X 14.0 = 42.03 X N = 3 X 14.0 = 42.0

9 X 0 = 9 X 16.0 = 144.09 X 0 = 9 X 16.0 = 144.0

Sum = 27.0 + 42.0 + 144.0 = Sum = 27.0 + 42.0 + 144.0 = 213.0213.0