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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