Chapter 10
 Identify the number that each word refers to:
 Couple - _______________
 Dozen - _______________
Use dimensional analysis to solve the following problems.
a. A cake recipe requires 8 eggs. How many dozens of
eggs are required to make 5 cakes?
 The mole represents a large number of extremely small particles.
 How is the mole used indirectly to count the number of particles of matter?
 What is a common everyday counting unit that the mole can be related to?
 How can moles be converted to number of representative particles and vice versa?
Vocabulary
 Avogadro’s Number
 Mole
 Molecule
SI base unit used to measure the
amount of substance.
1 mole = 6.022 x 1023
1 mole =
602,213,670,000,000,000,000,000
Abbreviated as mol
1 mole
THE MOLE IN PERSPECTIVE
1. One mole of paper would make a stack that would reach to the
moon more than 80 billion times
2. One mole of grains of sand would be more than all of the sand
on Miami Beach
3. One mole of blood cells would be more than the total number
of blood cells found in every human on earth
THE MOLE IN PERSPECTIVE
4. A one liter bottle of water contains 55.5 moles of water
5. One mole of seconds is about 19 quadrillion years,
4,240,666 times the age of the earth, or 954,150 times the
age of the universe itself
6. One mole of cents could repay the United States National
Debt 86 million times
MOLES & PARTICLES
 How many molecules are in 3.0 moles of H2O?
 How many moles of Aluminum, are in 4.02 x 1023 atoms of Al?
Section 2
 Why can the mass of an atom be related to the mass of a mole of atoms?
 How can the number of moles be converted to the mass of an element and vice
versa?
 How can the number of moles be converted to the number of atoms of an
element and vice versa?
Vocabulary
 Conversion Factor
 Molar Mass
MOLAR MASS:
 The mass of one mole of pure substance
 Units are always expressed as grams per mole (g/mol)
 Ex. Lithium = 6.94 g/mol
CALCULATE THE MOLAR MASS OF:
 Cu
 NaCl
 Ca2SO4
 Al(NO3)3
MOLAR CONVERSIONS:
 How many moles of oxygen in 3.98 g of oxygen?
 How many moles of carbon in 5.01 grams of carbon?
 Calculate the molar mass of Au (gold).
 How many grams are in two moles of Au?
MOLES & MASS
 What is the mass of 3.0 mols of NaCl?
 How many mols are in 30.0 g of H2O?
MOLES & PARTICLES & MASS
 Calculate the mass of 3.7 x 1024 molecules of MgCl2.
 How many atoms are in 100.0g of Silver?
Section 3
 What are the mole relationships shown by a chemical formula?
 How is the molar mass of a compound calculated?
 How can the number of moles be converted to the mass of a compound and vice versa?
 What conversion factors are applied to determine the number of atoms in a known mass of
compound?
Vocabulary
 Representative particle
 Chemical formulas give the relative numbers of atoms or moles of
each element in a compound
 Always a whole number ratio.
 Example:
 n determine the formula for the compound by knowing the relative
number of moles of each element in a compound.
Section 4
 What is mean by the percent composition of a compound?
 How can the empirical and molecular formulas for a compound be determined
from mass percent and actual mass data?
Vocabulary
 Percent by mass
 Percent composition
 Empirical formula
 Molecular formula
 Percent by mass of each element in a compound.
 % composition of any pure substance is always constant,
whatever the source or sample size.
 Useful in identifying the characteristic of any substance.
 Used by investigators from many fields, Analytical chemistry,
forensics etc. to determine the identity of unknown materials.
 Remember that percentage of anything is part over whole:
 For elements in a compound, do mass of element over mass
of compound.
 Calculate the percentage composition of each element in
NaNO3.
 27.05%Na, 16.48% N, 56.47% O
 Calculate the percentage composition of Oxygen in
Ag2SO4.

69.19% Ag, 10.28% S, 20.52% O
 Empirical formulas – consists of the symbols for the
elements combined in a compound, with subscripts
showing the smallest whole-number ratio of the different
atoms in the compound.
 Molecular Formulas – a multiple of the empirical formula.
 Determine the mass of each element
 Convert into moles
 Divide by the smallest mole or the elements present
 Determine the ratio
 Write the formula (Usually elements are listed from left to right on
the Periodic Table of Elements)
 Determine the empirical formula of a compound that is composed of 36.5%
sodium, 25.4 % sulfur, and 38.1 % oxygen.
 STEP 1: Find the number of moles of each element present.
Since the amount of each element is given in percentage, you must convert the
percentage to a mass. If 100 grams of the sample are assumed, the percentages
given are the same as grams.
 STEP 2: Determine the whole number mole ratio.
Divide each mole number by the smallest mole number.
Na2SO3
 STEP 3: Use the mole ratio for the subscripts of each
element in the formula.
 A compound is analyzed and found to contain 36.70% K, 33.27% Cl,
and 30.03% O. What is the empirical formula of the compound?
 A 60.00 g sample of tetramethyllead, a gasoline additive, is found to
contain 38.46 g of lead, 17.82 of carbon, and hydrogen. Find its
empirical formula.
Section 5
 What is a hydrate and how does its name relate to its
composition?
 How is the formula of a hydrate determined from laboratory
data?
Vocabulary
 Crystal lattice
 hydrate
 Must drive off the water by heating the compound
 Substance remaining after heating is anhydrous (without water)
 Example: Hydrated cobalt (II) chloride is a pink solid that turns a
deep blue when the water of hydration is driven off and anhydrous
cobalt (II) Chloride is produced.
 To determine the formula for a hydrate, you must
determine the number of moles of water associated with
one mole of the hydrate.
 2.50 g CuSO4 · x H20
 0.91 g H20 (Hydrate – Anhydrous)
 1.59 g CuSO4
0.91 𝑔 𝐻2 𝑂 1 𝑚𝑜𝑙 𝐻2 𝑂
×
= 0.0506 𝑚𝑜𝑙 𝐻2 𝑂
1
18.0 𝑔 𝐻2 𝑂
1.59 𝑔 𝐶𝑢𝑆𝑂4
1 𝑚𝑜𝑙 𝐶𝑢𝑆𝑂4
×
= 0.0100 𝑚𝑜𝑙 𝐶𝑢𝑆𝑂4
1
159.6 𝑔 𝐶𝑢𝑆𝑂4
CuSO4 · 5 H20
0.0506
0.0100
= 5 mol 𝐻2 𝑂
0.0100
= 1 𝑚𝑜𝑙 𝐶𝑢𝑆𝑂4
0.0100
 Drying Agents:
 Storage of solar energy