Avogadro’s Number

6.02 X 1023

1 Mole

6.02 X 1023

0.5 Mole

3.01 X 1023

0.25 Mole

1.50 X 1023

2.0 Mole

12.04 X 1023

Or1.204 X 1024

1.0 Mole of any gas at STP

22.4 Liters

STP

Standard Temperature = 0CStandard 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 H2O

2 X H = 2 X 1.0 = 2.01 X O = 1 X 16.0 = 16.0

Sum = 18.0

Formula Mass of NH3

3 X H = 3 X 1.0 = 3.01 X N = 1 X 14.0 = 14.0

Sum = 17.0

Formula Mass of CO2

1 X C = 1 X 12.0 = 12.02 X O = 2 X 16.0 = 32.0

Sum = 44.0

Count up the atoms in (NH4)2SO4

For Paren: SubInside X Suboutside

N: 2 S: 1H: 8 O: 4

Count up the atoms in 2Mg3(PO4)2

For Paren: SubInside X Suboutside

Coefficients X subs in formula

Mg: 6 P: 4 O: 16

# of Moles

# of Grams

# ofParticles

# ofLiters (gas)

X 6.02 X 1023

X Formula Mass

X 22.4 L/mole¸ by 6.02 X 1023

byformula mass

by22.4

Percent

Part X 100% Whole

Percent H in H2O

Part X 100% = 2 X 100%

Whole 18

Percent O in H2O

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

CuSO4•5H2O

Formula of a hydrated salt. • means “is associated with.”H2O molecules are stuffed in

the empty spaces.

Formula mass of CuSO4•5H2O

Mass of CuSO4 plus mass of 5 water molecules.

249.6 grams/mole

Percent H2O in CuSO4•5H2O

Part X 100% = 90 X 100% Whole 249.6

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?

H2O H2O2 CH4 C2H6

C6H12O6 KCl P4O10 CaF2

Given empirical formula & Formula Mass, find Molecular

Formula

1) Find empirical mass2) Divide formula mass/empirical

mass3) Multiply subscripts in empirical

formula by answer in step 2

Empirical formula = CH & Formula Mass = 78,

find Molecular Formula

1) Empirical mass = 132) Divide formula

mass/empirical mass = 78/13 = 6

3) Multiply subscripts: C6H6

12 grams of hydrated salt is heated. After heating the mass is 8.0 grams. What is the percent salt & the percent H2O?

1)Mass of H2O = 12 – 8 = 4 g

2)Percent H2O = 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

O2

1 molecule of O2 or 1 mole of O2

2 atoms per molecule

O3

1 molecule of O3 or 1 mole of O3

3 atoms per molecule