Title: Chemistry: Matter and Change
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2Chapter Menu
The Mole
Section 10.1 Measuring Matter Section 10.2 Mass
and the Mole Section 10.3 Moles of
Compounds Section 10.4 Empirical and Molecular
Formulas Section 10.5 Formulas of Hydrates
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3Section 10-1
Section 10.1 Measuring Matter
- Explain how a mole is used to indirectly count
the number of particles of matter.
molecule two or more atoms that covalently bond
together to form a unit
- Relate the mole to a common everyday counting
unit. - Convert between moles and number of
representative particles.
mole Avogadros number
Chemists use the mole to count atoms, molecules,
ions, and formula units.
4Section 10-1
Counting Particles
- Chemists need a convenient method for accurately
counting the number of atoms, molecules, or
formula units of a substance.
- The mole is the SI base unit used to measure the
amount of a substance. - 1 mole is the amount of atoms in 12 g of pure
carbon-12, or 6.02 ? 1023 atoms. - The number is called Avogadros number.
5Section 10-1
Converting Between Moles and Particles
- Conversion factors must be used.
Number of molecules in 3.50 mol of sucrose
6Section 10-1
Converting Between Moles and Particles (cont.)
- Use the inverse of Avogadros number as the
conversion factor.
7Section 10-1
Section 10.1 Assessment
What does the mole measure? A. mass of a
substance B. amount of a substance C. volume of
a gas D. density of a gas
- A
- B
- C
- D
8Section 10-1
Section 10.1 Assessment
- A
- B
- C
- D
9End of Section 10-1
10Section 10-2
Section 10.2 Mass and the Mole
- Relate the mass of an atom to the mass of a mole
of atoms.
conversion factor a ratio of equivalent values
used to express the same quantity in different
units
- Convert between number of moles and the mass of
an element. - Convert between number of moles and number of
atoms of an element.
molar mass
A mole always contains the same number of
particles however, moles of different substances
have different masses.
11Section 10-2
The Mass of a Mole
- 1 mol of copper and 1 mol of carbon have
different masses.
- One copper atom has a different mass than 1
carbon atom.
12Section 10-2
The Mass of a Mole (cont.)
- Molar mass is the mass in grams of one mole of
any pure substance.
- The molar mass of any element is numerically
equivalent to its atomic mass and has the units
g/mol.
13Section 10-2
Using Molar Mass
3.00 moles of copper has a mass of 191 g.
14Section 10-2
Using Molar Mass (cont.)
- Convert mass to moles with the inverse molar mass
conversion factor.
- Convert moles to atoms with Avogadros number as
the conversion factor.
15Section 10-2
Using Molar Mass (cont.)
- This figure shows the steps to complete
conversions between mass and atoms.
16Section 10-2
Section 10.2 Assessment
The mass in grams of 1 mol of any pure substance
is A. molar mass B. Avogadros number
C. atomic mass D. 1 g/mol
- A
- B
- C
- D
17Section 10-2
Section 10.2 Assessment
Molar mass is used to convert what? A. mass to
moles B. moles to mass C. atomic weight
D. particles
- A
- B
- C
- D
18End of Section 10-2
19Section 10-3
Section 10.3 Moles of Compounds
- Recognize the mole relationships shown by a
chemical formula.
- Calculate the molar mass of a compound.
- Convert between the number of moles and mass of a
compound. - Apply conversion factors to determine the number
of atoms or ions in a known mass of a compound.
representative particle an atom, molecule,
formula unit, or ion
20Section 10-3
Section 10.3 Moles of Compounds (cont.)
The molar mass of a compound can be calculated
from its chemical formula and can be used to
convert from mass to moles of that compound.
21Section 10-3
Chemical Formulas and the Mole
- Chemical formulas indicate the numbers and types
of atoms contained in one unit of the compound.
- One mole of CCl2F2 contains one mole of C atoms,
two moles of Cl atoms, and two moles of F atoms.
22Section 10-3
The Molar Mass of Compounds
- The molar mass of a compound equals the molar
mass of each element, multiplied by the moles of
that element in the chemical formula, added
together.
- The molar mass of a compound demonstrates the law
of conservation of mass.
23Section 10-3
Converting Moles of a Compound to Mass
- For elements, the conversion factor is the molar
mass of the compound.
- The procedure is the same for compounds, except
that you must first calculate the molar mass of
the compound.
24Section 10-3
Converting the Mass of a Compound to Moles
- The conversion factor is the inverse of the molar
mass of the compound.
25Section 10-3
Converting the Mass of a Compound to Number of
Particles
- Convert mass to moles of compound with the
inverse of molar mass.
- Convert moles to particles with Avogadros number.
26Section 10-3
Converting the Mass of a Compound to Number of
Particles (cont.)
- This figure summarizes the conversions between
mass, moles, and particles.
27Section 10-3
Section 10.3 Assessment
How many moles of OH ions are in 2.50 moles of
Ca(OH)2? A. 2.00 B. 2.50 C. 4.00 D. 5.00
- A
- B
- C
- D
28Section 10-3
Section 10.3 Assessment
How many particles of Mg are in 10 moles of
MgBr2? A. 6.02 ? 1023 B. 6.02 ? 1024 C. 1.20
? 1024 D. 1.20 ? 1025
- A
- B
- C
- D
29End of Section 10-3
30Section 10-4
Section 10.4 Empirical and Molecular Formulas
- Explain what is meant by the percent composition
of a compound.
percent by mass the ratio of the mass of each
element to the total mass of the compound
expressed as a percent
- Determine the empirical and molecular formulas
for a compound from mass percent and actual mass
data.
percent composition empirical formula molecular
formula
A molecular formula of a compound is a
whole-number multiple of its empirical formula.
31Section 10-4
Percent Composition
- The percent by mass of any element in a compound
can be found by dividing the mass of the element
by the mass of the compound and multiplying by
100.
32Section 10-4
Percent Composition (cont.)
- The percent by mass of each element in a compound
is the percent composition of a compound.
- Percent composition of a compound can also be
determined from its chemical formula.
33Section 10-4
Empirical Formula
- The empirical formula for a compound is the
smallest whole-number mole ratio of the elements.
- You can calculate the empirical formula from
percent by mass by assuming you have 100.00 g of
the compound. Then, convert the mass of each
element to moles. - The empirical formula may or may not be the same
as the molecular formula. - Molecular formula of hydrogen peroxide H2O2
- Empirical formula of hydrogen peroxide HO
34Section 10-4
Molecular Formula
- The molecular formula specifies the actual number
of atoms of each element in one molecule or
formula unit of the substance.
- Molecular formula is always a whole-number
multiple of the empirical formula.
35Section 10-4
Molecular Formula (cont.)
36Section 10-4
Section 10.4 Assessment
What is the empirical formula for the compound
C6H12O6? A. CHO B. C2H3O2 C. CH2O D. CH3O
- A
- B
- C
- D
37Section 10-4
Section 10.4 Assessment
Which is the empirical formula for hydrogen
peroxide? A. H2O2 B. H2O C. HO D. none of
the above
- A
- B
- C
- D
38End of Section 10-4
39Section 10-5
Section 10.5 Formulas of Hydrates
- Explain what a hydrate is and relate the name of
the hydrate to its composition.
crystal lattice a three-dimensional geometric
arrangement of particles
- Determine the formula of a hydrate from
laboratory data.
hydrate
Hydrates are solid ionic compounds in which water
molecules are trapped.
40Section 10-5
Naming Hydrates
- A hydrate is a compound that has a specific
number of water molecules bound to its atoms.
- The number of water molecules associated with
each formula unit of the compound is written
following a dot. - Sodium carbonate decahydrate Na2CO3 10H2O
41Section 10-5
Naming Hydrates (cont.)
42Section 10-5
Analyzing a Hydrate
- When heated, water molecules are released from a
hydrate leaving an anhydrous compound.
- To determine the formula of a hydrate, find the
number of moles of water associated with 1 mole
of hydrate.
43Section 10-5
Analyzing a Hydrate (cont.)
- Heat to drive off the water.
- Weigh the anhydrous compound.
- Subtract and convert the difference to moles.
- The ratio of moles of water to moles of anhydrous
compound is the coefficient for water in the
hydrate.
44Section 10-5
Use of Hydrates
- Anhydrous forms of hydrates are often used to
absorb water, particularly during shipment of
electronic and optical equipment.
- In chemistry labs, anhydrous forms of hydrates
are used to remove moisture from the air and keep
other substances dry.
45Section 10-5
Section 10.5 Assessment
Heating a hydrate causes what to happen?
A. Water is driven from the hydrate. B. The
hydrate melts. C. The hydrate conducts
electricity. D. There is no change in the
hydrate.
- A
- B
- C
- D
46Section 10-5
Section 10.5 Assessment
A hydrate that has been heated and the water
driven off is called A. dehydrated compound
B. antihydrated compound C. anhydrous compound
D. hydrous compound
- A
- B
- C
- D
47End of Section 10-5
48Resources Menu
Chemistry Online Study Guide Chapter
Assessment Standardized Test Practice Image
Bank Concepts in Motion
49Study Guide 1
Section 10.1 Measuring Matter
Key Concepts
- The mole is a unit used to count particles of
matter indirectly. One mole of a pure substance
contains Avogadros number of particles.
- Representative particles include atoms, ions,
molecules, formula units, electrons, and other
similar particles. - One mole of carbon-12 atoms has a mass of exactly
12 g. - Conversion factors written from Avogadros
relationship can be used to convert between moles
and number of representative particles.
50Study Guide 2
Section 10.2 Mass and the Mole
Key Concepts
- The mass in grams of 1 mol of any pure substance
is called its molar mass.
- The molar mass of an element is numerically equal
to its atomic mass. - The molar mass of any substance is the mass in
grams of Avogadros number of representative
particles of the substance. - Molar mass is used to convert from moles to mass.
The inverse of molar mass is used to convert from
mass to moles.
51Study Guide 3
Section 10.3 Moles of Compounds
Key Concepts
- Subscripts in a chemical formula indicate how
many moles of each element are present in 1 mol
of the compound.
- The molar mass of a compound is calculated from
the molar masses of all of the elements in the
compound. - Conversion factors based on a compounds molar
mass are used to convert between moles and mass
of a compound.
52Study Guide 4
Section 10.4 Empirical and Molecular Formulas
Key Concepts
- The percent by mass of an element in a compound
gives the percentage of the compounds total mass
due to that element.
- The subscripts in an empirical formula give the
smallest whole-number ratio of moles of elements
in the compound. - The molecular formula gives the actual number of
atoms of each element in a molecule or formula
unit of a substance. - The molecular formula is a whole-number multiple
of the empirical formula.
53Study Guide 5
Section 10.5 Formulas of Hydrates
Key Concepts
- The formula of a hydrate consists of the formula
of the ionic compound and the number of water
molecules associated with one formula unit.
- The name of a hydrate consists of the compound
name and the word hydrate with a prefix
indicating the number of water molecules in 1 mol
of the compound. - Anhydrous compounds are formed when hydrates are
heated.
54Chapter Assessment 1
What does Avogadros number represent? A. the
number of atoms in 1 mol of an element B. the
number of molecules in 1 mol of a compound
C. the number of Na ions in 1 mol of NaCl (aq)
D. all of the above
- A
- B
- C
- D
55Chapter Assessment 2
The molar mass of an element is numerically
equivalent to what? A. 1 amu B. 1 mole C. its
atomic mass D. its atomic number
- A
- B
- C
- D
56Chapter Assessment 3
How many moles of hydrogen atoms are in one mole
of H2O2? A. 1 B. 2 C. 3 D. 0.5
- A
- B
- C
- D
57Chapter Assessment 4
What is the empirical formula of Al2Br3?
A. AlBr B. AlBr3 C. Al2Br D. Al2Br3
- A
- B
- C
- D
58Chapter Assessment 5
What is an ionic solid with trapped water
molecules called? A. aqueous solution
B. anhydrous compound C. hydrate D. solute
- A
- B
- C
- D
59STP 1
Two substances have the same percent by mass
composition, but very different properties. They
must have the same ____. A. density
B. empirical formula C. molecular formula
D. molar mass
- A
- B
- C
- D
60STP 2
How many moles of Al are in 2.0 mol of Al2Br3?
A. 2 B. 4 C. 6 D. 1
- A
- B
- C
- D
61STP 3
How many water molecules are associated with 3.0
mol of CoCl2 6H2O? A. 18 B. 1.1 ? 1025
C. 3.6 ? 1024 D. 1.8 ? 1024
- A
- B
- C
- D
62STP 4
How many atoms of hydrogen are in 3.5 mol of
H2S? A. 7.0 ? 1023 B. 2.1 ? 1023 C. 6.0 ?
1023 D. 4.2 ? 1024
- A
- B
- C
- D
63STP 5
Which is not the correct formula for an ionic
compound? A. CO2 B. NaCl C. Na2SO4 D. LiBr2
- A
- B
- C
- D
64IB Menu
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65IB 1
66IB 2
67IB 3
68IB 4
69IB 6
70IB 7
71CIM
Figure 10.6 Molar Mass Table 10.1 Formulas of
Hydrates
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