MOLEChapter 10
DO NOW: 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?
BIG IDEAThe mole represents a large number of extremely small particles.
SECTION 1: MEASURING MATTER
ESSENTIAL QUESTIONS & VOCABULARY 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
THE MOLE 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
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
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
THE MOLE IN PERSPECTIVE
MOLES TO PARTICLES
PARTICLES TO MOLES
MOLES & PARTICLESHow many molecules are in 3.0 moles of H2O?
How many moles of Aluminum, are in 4.02 x 1023 atoms of Al?
MASS AND THE MOLES
Section 2
ESSENTIAL QUESTIONS & VOCABULARY
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
EXAMPLE: CALCULATE THE MOLAR MASS OF CH4
CALCULATE THE MOLAR MASS OF:Cu
NaCl
Ca2SO4
Al(NO3)3
MOLAR CONVERSIONS:
MOLES TO MASS
MASS TO MOLES How many moles of oxygen in 3.98 g of oxygen?
How many moles of carbon in 5.01 grams of carbon?
PRACTICE PROBLEM
Calculate the molar mass of Au (gold).
How many grams are in two moles of Au?
MOLES & MASSWhat is the mass of 3.0 mols of NaCl?
How many mols are in 30.0 g of H2O?
MOLES & PARTICLES & MASSCalculate the mass of 3.7 x 1024 molecules of MgCl2.
How many atoms are in 100.0g of Silver?
MOLES OF COMPOUNDS
Section 3
ESSENTIAL QUESTIONS & VOCABULARY
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 AND THE MOLE
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.
EMPIRICAL AND MOLECULAR FORMULASSection 4
ESSENTIAL QUESTIONS & VOCABULARY
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 COMPOSITIONPercent 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.
PERCENT COMPOSITIONRemember that percentage of anything is part over whole:
For elements in a compound, do mass of element over mass of compound.
SAMPLE PROBLEMSCalculate 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 VS. MOLECULAR FORMULASEmpirical 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.
GUIDELINES FOR DETERMINING 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)
FINDING EMPIRICAL FORMULA – STEP 1 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.
FINDING EMPIRICAL FORMULA – STEP 2 & 3STEP 2: Determine the whole number mole ratio.Divide each mole number by the smallest mole number.
STEP 3: Use the mole ratio for the subscripts of each element in the formula.
Na2SO3
EMPIRICAL FORMULA EXAMPLE 2
EMPIRICAL FORMULA: SAMPLE PROBLEMS
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.
FORMULAS OF HYDRATES
Section 5
ESSENTIAL QUESTIONS & VOCABULARY
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
NAMING HYDRATES
NAMING HYDRATES
ANALYZING A 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.
FORMULA FOR A HYDRATE
To determine the formula for a hydrate, you must
determine the number of moles of water associated
with one mole of the hydrate.
COPPER SULFATE HYDRATE EXAMPLE2.50 g CuSO4 · x H201.59 g CuSO4
0.91 g H20 (Hydrate – Anhydrous)
mol
0.01000.0100
=1𝑚𝑜𝑙𝐶𝑢𝑆𝑂4
CuSO4 · 5 H20
HYDRATES – COPPER SULFATE HYDRATE
USES OF HYDRATES
Drying Agents:
Storage of solar energy
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