Download 7-1 Avogadro`s Number and Molar Conversions Objectives: • Identify

HOLT CHEMISTRY
CHAPTER 07
THE MOLE AND CHEMICAL COMPOSITION
7-1 Avogadro’s Number and Molar Conversions
Objectives:
 Identify the mole as the unit used to count particles, whether atoms, ion, or molecules.
 Use Avogadro’s number to convert between amount in moles and number of particles.
 Solve problems converting to convert between amount in moles, and number of particles
using Avogadro’s number and molar mass.
A Avogadro’s Number and the Mole
1. The Mole is a Counting Unit
a.) The SI unit for amount is the mole.
b.) The number of particles in a mole is called Avogadro’s Number.
c.) The most recent measurement of Avogadro’s Number is 6.02214199 x 1023.
d.) We will use 6.022 x 1023
2. Amount in Moles Can Be Converted to Number of Particles - Board
3. Choose the Conversion Factor That Cancels the Given Units - Board
4. Number of Particles Can Be Converted to Amount in Moles - Board
B Molar Mass Relates Moles to Grams
1. Amount in Moles Can Be Converted to Mass
a.) The molar mass, or mass in grams of one mole of an element or compound is
numerically equal to the atomic mass of monatomic elements and the formula
mass of compounds and diatomic elements.
b.) To find a monatomic element’s molar mass, use the atomic mass, but instead of
having units of amu, the molar mass will have units of g/mol.
c.) Board
2. The Mole Plays a Central Part in Chemical Conversions - Board
3. Mass Can Be Converted to Amount in Moles - Board
4. Remember to Round Consistently – Rules of Significant Figures.
7-2 Relative Atomic Mass and Chemical Formulas
Objectives:
 Use a periodic table or isotopic composition data to determine the average atomic masses
of elements.
 Infer information about a compound from its chemical formula.
 Determine the molar mass of a compound from its formula.
A Average Atomic Mass and the Periodic Table
1. Most Elements Are Mixtures of Isotopes.
2. The periodic table reports the average atomic mass in amu.
3. To find a monatomic element’s molar mass, use the average atomic mass, but instead
of having units of amu, the molar mass will have units of g/mol.
B Chemical Formulas and Moles
1. Formulas Express Composition
a.) The chemical formula gives the ratio of atoms in the compound.
2. Formulas Give Ratios of Polyatomic Ions.
a.) The chemical formula also gives the ratio of polyatomic ion in the compound.
b.) If more than one polyatomic ion is in a chemical formula, it is separated by
parenthesis. - Board
3. Formulas Are Used to Calculate Molar Mass. - Board
7-3 Formulas and Percentage Composition
Objectives:
 Determine a compound’s empirical formula from its percentage.
 Determine the molecular formula or formula unit of a compound from its empirical
formula.
 Calculate percentage composition of a compound from its molecular formula or formula
unit.
A Using Analytical Data
1. One way to perform chemical analysis is to determine percent composition.
B Determining Empirical Formulas
1. The empirical formula shows the simplest ratio of atoms in the compound.
2. - Board
C Molecular Formulas Are Multiples of Empirical Formulas- Board
D Chemical Formulas Can Give Percentage Composition- Board