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The Mole
The Mole
The Number of Particles in a Mole
1 mole (mol) = 6.02 x 1023
representative particles of a substance
Representative particles are usually atoms or molecules.
→ For most elements it is the atom.
Representative →
particles
usuallymolecules:
atoms or molecules
Sevenare
diatomic
H2, N2, O2, F2, Cl2, Br2, & I2.
→ For most elements it is the atom
→ Seven diatomic molecules: H2, N2, O2, F2, Cl2, Br2, & I2
The Mole
Avogadro's Number (6.02 x 1023) was experimentally determined
Representative Particles and Moles
Substance
Representative
Particle
Chemical
Formula
Particles in
1.00 mol
Atomic Nitrogen
Atom
N
6.02 x 1023
Nitrogen gas
Molecule
N2
6.02 x 1023
Water
Molecule
H2O
6.02 x 1023
Calcium ion
Ion
Ca2+
6.02 x 1023
Calcium fluoride
Formula unit
CaF2
6.02 x 1023
Sucrose
Molecule
C12H22O11
6.02 x 1023
The Mole
Example problem:
How many moles of magnesium is 1.25 x 1023 atoms of magnesium?
The Mole
Example problem:
How many molecules are in 2.12 mol of propane (C3H8)?
The Mole
Molecular Weight (MW) (molar mass)
Molecular Weight is determined by adding up all of the atomic
masses for the molecule or compound.
Ex. Molar mass of CaCl2
x2
40.08
+
70.90
=
110.98 g/mol
The Mole
Example problem:
Calculate the molar mass of NaCl
Example problem:
Calculate the molar mass of water
The Mole
Example problem:
How many grams are in 9.45 mol of dinitrogen trioxide? (N2O3)
The Mole
Example problem:
Find the number of moles in 92.2 grams of iron (III) oxide. (rust)(Fe2O3)