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Chapter 10: Chemical Quantities
The Mole
What is a mole?The SI unit that represents the amount
of a substance that contains 6.02 x 1023 representative particles of that substance.
What is Avogadro’s Number? The number of particles contained in
one mole of a substance.6.02 x 1023 particles602,000,000,000,000,000,000,000
What is a Representative Particle? Atom:
The smallest particle of an element Molecule:
Group of atoms joined together by covalent bonds
Formula unit:Lowest ratio of elements in ionic bonds
Particle:This word can be used for any of the above
words
Atomic or Formula Mass Mass of one single representative particle
of a substance Measured in atomic mass units (amu)
How do you find Atomic or Formula Mass? Add up the amu for every part of the
substance: Find the amu on the Periodic Table
C
12.01 amu
NaCl
22.99 amu + 35.45 amu = 58.44 amu
H2O
(1.01 amu x 2) + 16.00 amu =
18.02 amu
Molar Mass The mass of one mole of any substance
Measured in grams/ mole Same as finding atomic mass, but change amu to
grams.
C 12.01 amu = 12.01 g/molNaCl58.44 amu = 58.44 g/mol
H2O18.02 amu = 18.02 g/mol
Converting # of Particles to # of Moles
Formula:
# of moles =
# of particles x
1 mole6.02 x 1023 particles
Sample Problem:
How many moles of NaCl are in 3.01x1023 formula units of NaCl?
Converting # of Moles to # of Particles
Formula:
# of particles =
# of moles x 6.02 x 1023 particles 1 mole
Sample Problem:
How many particles are in 3 moles of water?
Converting # of Moles to Mass
Formula:
Mass (g) =
# of moles x Molar mass (g) 1 mole
Sample Problem:
What is the mass of 1 mole of LiOH?
Converting Mass to # of Moles
Formula:
# of moles =
Mass (g) x 1 mole Mass (g)
Sample Problem:
How many moles of NaCl are in 174.22 grams of NaCl?
Mole-Volume Relationship
Avogadro’s Hypothesis:At standard temperature and pressure (STP)
1 mole of any gas occupies the same volume.STP: 0oC and 1 atm
At STP, 1 mole or 6.02 x 1023 particles, of ANY gas, has a volume of 22.4 L.
22.4 L is called the molar volume of a gas.
Converting # of Moles of gas to Volume
Formula:
Volume of gas =
moles of gas x22.4 L 1 mole
Sample Problem:
What is the volume, in liters, of 0.60 mol of SO2 gas at STP?
Converting Volume of gas to Moles
Formula:
Moles of gas =volume of gas x
1 mole 22.4 L
Sample Problem:
If you collect 8.00 L of O2 gas, how many moles have you collected?
Calculating Molar Mass from Density
Formula:
=22.4 L 1 mole
grams mole
grams L
Molar mass
Density
Sample Problem:
What is molar mass of a gas with a density of 2.86 g/L at STP?
Percent Composition of a Substance Percent Composition=
Mass of element in the compound x 100
Molar Mass of Compound
Sample Problem
Find the % composition of H and O in water