To understand the definition of molar mass

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Objectives

1. To understand the definition of molar mass
2. To learn to convert between moles and mass
3. To learn to calculate the mass percent of an
   element in a compound

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A. Molar Mass

• A compound is a collection of atoms bound
  together.

• The molar mass of (one mole of) a compound is
  obtained by summing the masses of the appropriate
  number of moles of component atoms.

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A. Molar Mass

• For compounds containing ions the molar mass is
  obtained by summing the masses of the component
  ions. This is sometimes called the formula weight.

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What is the Molar Mass of the following Compounds?

• Na3N
• CS2
• NH4Br
• C2H5OH
• H2SO3
• H2SO4
• MgSO4

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A. Molar Mass
Calculations Using Molar Mass

• Moles of a compound (g)

• Mass of a sample (g) moles of sample (mol)
  x molar mass of compound (g/mol)

• Number of atoms in moles of a sample number of
  moles x number of atoms in formula x
  Avogadros number

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Relationships Between Moles, Mass and Atoms
Avogadros Number 6.022x1023
Atomic Mass from Periodic Table
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Relationships Between Moles, Mass, Molecules and
Atoms
Molar Mass using Periodic Table
Avogadros Number 6.022x1023
Molecular Formula
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B. Percent Composition of Compounds

• Percent composition consists of the mass percent
  of each element in a compound

• Mass percent

What are the mass percentages of C, H and O in
Ethanol?
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Calculate the Mass Percent of These Compounds

• LiBr
• CuOH
• SrSO4
• C2H4O
• C6H12O6