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Chemical Quantities Mole Mass Relationships

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					Chapter 10: Chemical Quantities

Mole-Mass Relationships
    Mrs. Russotto
Mole – Mass Relationships
   Use the molar mass of an element or compound to
    convert between the mass of a substance and the moles
    of a substance
    Converting Moles to Mass
   Aluminum satellite dishes are resistant to
    corrosion because the aluminum reacts with
    oxygen in the air to form a coating of aluminum
    oxide (Al2O3). What is the mass of 9.45 mol of this
    tough, resistant coating?
        Known                       Unknown
        9.45 mol Al2O3              ? g Al2O3
                                    Molar mass of Al2O3
      Calculate Molar Mass
    Al = 27.0    X2      = 54.0 g        Therefore:
    O = 16.0     X 3 + = 48.0 g           102.0 g Al2O3 = 1 mol Al2O3

                       102.0 g
9.45 mol Al2O3   102.0 g Al2O3          =
                 1 mol Al2O3

        963.9 g Al2O3   = 964 g Al2O3
Try this with your partner…
   Find the mass of 0.452 mol C20H42 in grams.
    Answer: 127 g C20H42
    Converting Mass to Moles
   When iron is exposed to air, it corrodes to form
    red-brown rust. Rust is iron(III) oxide (Fe2O3).
    How many moles of iron(III) oxide are contained in
    92.2 g of pure Fe2O3?
       Known                   Unknown
       92.2 g Fe2O3            ? mol Fe2O3
                               Molar mass of Fe2O3
      Calculate Molar Mass
    Fe = 55.8   X 2 = 111.6 g Therefore:
    O = 16.0    X 3 + = 48.0 g 159.6 g Fe2O3 = 1 mol Fe2O3
                       159.6 g
92.2 g Fe2O3   1 mol Fe2O3               =
               159.6 g Fe2O3

  0.577694 mol Fe2O3 = 0.578 mol Fe2O3
Try this with your partner…
   Calculate the number of moles in 75.0 g of
    magnesium fluoride.
    Answer: 1.20 mol MgF2

				
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