Avogadro’s Number 6.02 X 10 23

1 Mole 6.02 X 10 23

0.5 Mole 3.01 X 10 23

0.25 Mole 1.50 X 10 23

2.0 Mole X Or X 10 24

1.0 Mole of any gas at STP 22.4 Liters

STP Standard Temperature = 0  C Standard Pressure = 1 atm

0.5 mole of any gas 11.2 Liters

2.0 mole of any gas 44.8 Liters

3.0 mole of any gas 67.2 Liters

0.25 mole of any gas 5.6 Liters

Gram Atomic Mass Mass of 1 mole of an element.

Formula Mass Sum of the masses of the elements in the compound

Formula Mass of H 2 O 2 X H = 2 X 1.0 = X O = 1 X 16.0 = 16.0 Sum = 18.0

Formula Mass of NH 3 3 X H = 3 X 1.0 = X N = 1 X 14.0 = 14.0 Sum = 17.0

Formula Mass of CO 2 1 X C = 1 X 12.0 = X O = 2 X 16.0 = 32.0 Sum = 44.0

Count up the atoms in (NH 4 ) 2 SO 4 For Paren: Sub Inside X Sub outside N: 2S: 1 H: 8O: 4

Count up the atoms in 2Mg 3 (PO 4 ) 2 For Paren: Sub Inside X Sub outside Coefficients X subs in formula Mg: 6P: 4O: 16

# of Moles # of Grams # of Particles # of Liters (gas) X 6.02 X X Formula Mass X 22.4 L/mole  by 6.02 X  by formula mass  by 22.4

Percent Part X 100% Whole

Percent H in H 2 O Part X 100% = 2 X 100% Whole 18

Percent O in H 2 O Part X 100% = 16 X 100% Whole 18

Empirical Formula smallest whole number ratio of the elements in a compound

Molecular Formula Gives exact composition of molecule

Covalent Compound Formula contains all nonmetals

Ionic Compound Formula contains metal plus nonmetal

CuSO 45H 2 O Formula of a hydrated salt. means “is associated with.” H 2 O molecules are stuffed in the empty spaces.

Formula mass of CuSO 45H 2 O Mass of CuSO 4 plus mass of 5 water molecules grams/mole

Percent H 2 O in CuSO 4 5H 2 O Part X 100% = 90 X 100% Whole249.6

Metals All elements to the left of the staircase except H

Nonmetals All elements to the right of the staircase plus H

Binary Compound Compound made from 2 elements

Which formulas are empirical? H 2 OH 2 O 2 CH 4 C 2 H 6 C 6 H 12 O 6 KClP 4 O 10 CaF 2

Given empirical formula & Formula Mass, find Molecular Formula 1)Find empirical mass 2)Divide formula mass/empirical mass 3)Multiply subscripts in empirical formula by answer in step 2

Empirical formula = CH & Formula Mass = 78, find Molecular Formula 1)Empirical mass = 13 2)Divide formula mass/empirical mass = 78/13 = 6 3)Multiply subscripts: C 6 H 6

12 grams of hydrated salt is heated. After heating the mass is 8.0 grams. What is the percent salt & the percent H 2 O? 1)Mass of H 2 O = 12 – 8 = 4 g 2)Percent H 2 O = 4/12 X 100% 3)Percent salt = 8/12 X 100%

He 1 atom of He or 1 mole of He 1 atom per molecule

O2O2 1 molecule of O 2 or 1 mole of O 2 2 atoms per molecule

O3O3 1 molecule of O 3 or 1 mole of O 3 3 atoms per molecule