# Chapter 10 Chemical Quantities

```Statement
Chemistry is a quantitative science.
A. Measuring Matter
A. Measuring Matter
1.
2. What is one way to measure matter?
One way to measure matter is to count how
many of something you have.
3. Statement
Knowing how the count, mass, and volume
of an item relate to a common unit allows
you to convert among these units.
This is called Dimensional Analysis.
Sample Problem 10.1
What is the mass of 90 average-size apples
if 1 dozen of the apples has a mass of 2.0
Kg?
(15 Kg)
Do the problems 1 and 2 at the bottom of
page 307.
How do chemists count the number of
atoms, molecules, or formula units in a
substance?
The chemists use a unit that is a specified
number of particles. The unit is called the
mole.
B. What is a Mole?
B. What is a Mole?
1.
2. What is a mole?
It represents 6.02 x 1023 particles of that
substance.
It is the SI unit for measuring the amount of a
substance.
B. What is a Mole?
B. What is a Mole?
3. What is the name of number of
representative particles in a mole?
It was named in honor of the Italian scientist
helped clarify the difference between
atoms and molecules.
4. What does the term representative
particle mean?
It refers to the species present in a
substance, usually atoms, molecules, or
formula units.
B. What is a Mole?
B. What is a Mole?
5. Statement
The mole allows chemists to count the
number of representative particles in a
substance.
6. Converting between Number of Particles
and Moles
1 mole = 6.02 x 1023 particles
Sample Problem 10.2
Converting Number of Atoms to Moles
Magnesium is a light metal used in the
manufacture of aircraft, automobile
wheels, and tools. How many moles of
magnesium is 1.25 x 1023 atoms of
magnesium?
Do Problems 3 and 4 at the bottom of
Page 309.
Sample Problem 10.3
Converting Moles to Number of Atoms
Propane is a gas used for cooking and
heating. How many atoms are in 2.12
moles of propane (C3H8)?
Do problems 5 and 6 at the bottom of
page 311.
What is Molar Mass?
It is the mass of a mole of a substance.
C. Molar Mass
1.
2. How do you determine the molar mass of
an element and of a compound?
The atomic mass of an element expressed in
grams on the Periodic table.
C. Molar Mass
To Calculate the molar mass of a
compound, do the following chart:
Symbol
Subscript
Atomic Mass
Total Mass
Sample Problem 10.4
Finding the Molar Mass of a Compound
The decomposition of hydrogen peroxide
(H2O2) provides sufficient energy to launch
a rocket. What is the molar mass of
hydrogen peroxide?
Do problems 7 and 8 at the bottom of
page 315.
10.1 Lesson Check
Do the following problems: 12, 13, 14, 15
A. The Mole-Mass Relationships
A. The Mole-Mass Relationships
How do you convert the mass of a
substance to the number of moles of the
substance?
Use the molar mass of an element or
compound to convert between the mass of
a substance and the moles of the
substance.
1.
Sample Problem 10.5
Converting Moles to mass
Items made out of aluminum are resistant to
corrosion because of the aluminum reacts
with oxygen in the air to form a coating of
aluminum oxide (AL2O3). This tough, resistant
coating prevents any further corrosion. What
is the mass, in grams, of 9.45 mole of
aluminum oxide?
Do Problems 16 and 17 at the bottom of page
318.
Sample Problem 10.6
Converting Mass to Moles
When iron is exposed to air, it corrodes to
form red-brown rust. Rust is iron (III) oxide
(Fe2O3). How many moles of iron (III) oxide
are contained in 92.2 grams of pure Fe2O3?
Do problems 18 and 19 at the bottom of
page 319.
It states that equal volumes of gases at the
same temperature and pressure contain
equal numbers of particles.
2. What is STP?
It is standard temperature and pressure. The
temperature is 0°C. Pressure is 101.3 kPa or 1
atmosphere (atm).
B. The Mole-Volume
Relationship
1.
B. The Mole-Volume
Relationship
3. What is molar volume? 22.4 L
Sample Problem 10.7
Calculating Gas Quantities at STP
Sulfur dioxide (SO2) is a gas produced by
burning coal. It is an air pollutant and one
of the causes of acid rain. Determine the
volume, in liters, of 0.60 mole SO2 at STP.
Do problems 20 and 21 at the bottom of
page 321.
Sample problem 10.8
Calculating the Molar Mass of a Gas at STP
The density of a gaseous compound
containing carbon and oxygen is found to
be 1.964 g/L at STP. What is the molar mass
of the compound?
Do problems 22 and 23 at the bottom of
page 322.
10.2 lesson Check
Do the following problems: 26, 27, 28, 29,
30, and 31.
A. % Composition of a CMPD
A. % Composition of a CMPD
What is percent composition?
It is the relative amounts of the elements in a
compound.
2. How do you calculate the percent
composition of a compound?
The percent by mass of an element in a
compound is the number of grams of the
element divided by the mass in grams of the
compound, multiplied by 100%.
1.
Sample Problem 10.9
Calculating Percent Composition from
Mass Data
When a 13.60-g sample of a compound
containing only magnesium and oxygen is
decomposed, 5.40 grams of oxygen is
obtained. What is the percent composition
of this compound?
Do problems 33 and 34 at the bottom of
page 326.
Sample Problem 10.10
Calculating Percent Composition from a
Formula
Propane (C3H8), the fuel commonly used in
gas grills, is one of the compounds
obtained from petroleum. Calculate the
percent composition of propane.
Do problems 35 and 36 at the bottom of
page 327.
Sample Problem 10.11
Calculating the Mass of an Element in a
Compound Using Percent Composition.
Calculate the mass of carbon and the
mass of hydrogen in 82.0 grams of
propane (C3H8).
Do problems 37 and 38 at the bottom of
page 329.
What is the empirical formula of a
compound?
It gives the lowest whole-number ratio of the
atoms or moles of the elements in a
compound.
2. How can you calculate the empirical
formula of a compound?
B. Empirical Formulas
B. Empirical Formulas
1.
Sample Problem 10.12
Determining the Empirical Formula of a
Compound
A compound is analyzed and found to
contain 25.9% nitrogen and 74.1% oxygen.
What is the empirical formula of the
compound?
Do problems 39 and 40 at the bottom of
page 331.
What is the molecular formula of a
compound?
It is a simple whole-number multiple of its
empirical formula.
It can be same as its experimentally
determined empirical formula.
C. Molecular Formulas
C. Molecular Formulas
1.
Sample problem 10.13
Finding the Molecular Formula of a
Compound
Calculate the molecular formula of a
compound whose molar mass is 60.0
g/mole and empirical formula is CH4N.
Do problems 41 and 42 at the bottom of
page 333.
10.3 Lesson Check
Do the following problems: 46, 47, and 48.
Study Guide on Page 336
Math Tune-Up: Mole Problems on Page 337
Lesson by Lesson on pages 338-342
Test on Chapter 10 Chemical Quantities
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