Chem 210FL lecture notes
7.1 The Mole
Chapter 7 Chemical Quantities Dr. Baxley Spring 2014
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Learning Goal: Use Avogadro's number to determine the number of particles in a mole
Familiar counting terms:
Avogadro’s number is equal to: ____________________________________________________________
A mole (mol) is a unit that represents ________________________________________________________________________
as there are carbon atoms in 12.01 g of carbon.
One mole of any element contains _________________________________________________ atoms of that element.
1 mol of Element
1 mol Mo
1 mol Au
Number of Atoms
= __________________________________________
= __________________________________________
Avogadro’s number can be used as a conversion factor. Write the two forms below:
Avogadro’s number converts the number of _________________________________________________________________ .
How many Cu atoms are in 0.50 mol of Cu?
Avogadro’s number converts the number of _________________________________________________________________ .
How many moles of CO2 are in 2.50 × 1024 molecules of CO2?
Learning Check:
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The number of atoms in 2.0 moles of aluminum is
A. 2.0 Al atoms
B. 3.0×1023 Al atoms
C. 1.2×1024 Al atoms
The subscripts in a chemical formula state two things:
1. ________________________________________________________________________________________________________________
2. ________________________________________________________________________________________________________________
Aspirin (acetyl salicylic acid) has the formula of C9H8O4.
How many moles of carbon and oxygen are in a 0.20 mol sample of aspirin?
7.2 Molar Mass
Learning Goal: Calculate the molar masses of molecules and compounds.
The molar mass is
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•
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the mass of __________________________________________________ of an element or compound
the mass of __________________________________________________ atoms of an element
the mass of __________________________________________________ molecules or formula units
To determine the molar mass of __________________________________________ ____________________________________ ,
just use the average atomic mass on the periodic table
To determine the molar mass of compounds, ________________________________________________________________
Calculate the molar mass of copper (II) sulfide.
Calculate the molar mass of iron (III) hydroxide.
Learning Check:
Calculate the molar mass of aluminum oxide.
Calculate the molar mass of calcium hydroxide.
7.3 Using Molar Mass As A Conversion Factor
Learning Goals:
Using molar mass,
• calculate the mass of a substance (in grams) from moles;
• calculate the number of moles of a substance from grams
The molar mass is a useful conversion factor
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•
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converts moles of a substance _________________________________________________
converts mass in grams of a substance to ____________________________________
Write the two forms of the conversion factors for the molar mass of Mg:
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What mass, in grams, is present in 2.50 moles of Mg?
What number of moles is present in 18.0 g of Mg?
Conversion factors are written for compounds in the same way as those written for elements.
Write the two forms of the conversions factors for the molar mass of water:
What mass, in grams, is present in 2.50 moles of water?
What number of moles is present in 18.0 g of water?
A 10.00-lb bag of table sugar contains 4536 g of sucrose, C12H22O11. How many molecules of sucrose
are present?
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