mass-mol_ mass-mass

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					 Bellwork:
    How is it possible for a jet airplane carrying
    110 tons of jet fuel to emit 340 tons of carbon
    dioxide?




 The fuel is a hydrocarbon that is about to be combusted.
 Combustion is a process in which oxygen combines with a
 hydrocarbon to produce carbon dioxide and water. As the carbon-
 based fuel combusts, each carbon is combined with two oxygen
 atoms that come from the air, so the overall mass seems to increase
 when compared to the starting amount of fuel. However, mass is
 conserved, because the oxygen was part of the original reactants, it
 just came from a different source.
 Bellwork:
 The disinfectant hydrogen peroxide, H2O2, decomposes
 to form water and oxygen gas. How many moles of O2
 will result from the decomposition of 5.0 mol of
 hydrogen peroxide?

         2H2O2(l)          2H2O(l) + O2(g)
        5.0 mol                       ? mol



                   1 mol O2
5.0 mol H2O2 x               = 2.5 mol O2
                  2 mol H2O2
 Bellwork:
 Zinc metal can be obtained from zinc oxide, ZnO, by reacting
  the oxide with the element carbon. The products of the
  reaction are Zn and CO2. What mass in grams of zinc oxide is
  needed to react completely with 5.00 mol of carbon?

        2ZnO(s) + C(s)           2Zn(s) + CO2(g)
          ?g       5.00 mol




               2 mol ZnO   81.39 g ZnO     814 g ZnO
5.00 mol C x             x             =
                 1 mol C   1 mol ZnO
Stoichiometry – Ch. 9

       I.   Stoichiometric
             Calculations

             (p. 275-287)
              OBJECTIVES
3.3.6 Calculate the amount in moles of a reactant or
      product from the mass of a different reactant
      or product.

3.3.7 Calculate the mass of a reactant or product
      from the mass of a different reactant or product.
Conversions of Mass to
Amounts in Moles
                Sample Problem 9-4
The first step in the industrial manufacture of nitric acid is the
 catalytic oxidation of ammonia.

      4NH3(g) + 5O2(g)               4NO(g) + 6H2O(g)
       824 g                           ? mol
The reaction is run using 824 g of NH3 and excess oxygen.

a. How many moles of NO are formed


               1 mol NH3     4 mol NO      48.4 mol NO
824 g NH3 x                x           =
               17.04 g NH3   4 mol NH3
                Sample Problem 9-4
The first step in the industrial manufacture of nitric acid is the
 catalytic oxidation of ammonia.

      4NH3(g) + 5O2(g)               4NO(g) + 6H2O(g)
       824 g                                      ? mol

The reaction is run using 824 g of NH3 and excess oxygen.

b. How many moles of H2O are formed?


               1 mol NH3     6 mol H2O     72.6 mol H2O
824 g NH3 x                x           =
               17.04 g NH3   4 mol NH3
     Additional Sample Problem #1
Chlorine gas can be produced commercially by passing an
 electric current through a concentrated solution of sodium
 chloride (brine).

  2NaCl(g) + 2H2O(l)            2NaOH(aq) + Cl2(g) + H2(g)
    250 g                                      ? mol

 a. If the brine contains 250 g of NaCl, how many moles
   of Cl2 can be produced?

               1 mol NaCl      1 mol Cl2     2.14 mol Cl2
250 g NaCl x                x            =
               58.44 g NaCl   2 mol NaCl
     Additional Sample Problem #1
Chlorine gas can be produced commercially by passing an
 electric current through a concentrated solution of sodium
 chloride (brine).

  2NaCl(g) + 2H2O(l)            2NaOH(aq) + Cl2(g) + H2(g)
    250 g                                               ? mol

 b. How many moles of H2 can be produced?


               1 mol NaCl      1 mol H2      2.14 mol Cl2
250 g NaCl x                x            =
               58.44 g NaCl   2 mol NaCl
Mass-Mass Calculations
                  Sample Problem 9-5
 Tin(II) fluoride, SnF2, is used in some toothpastes. It is made by
   the reaction of tin with hydrogen fluoride according to the
   following equation.

        Sn(s) + 2HF(g)             SnF2(s) + H2(g)
                  30.00 g            ?g
 How many grams of SnF2 are produced from the reaction of
  30.00 g of HF with Sn?



               1 mol HF     1 mol SnF2   156.71 g SnF2 =   117.5 g SnF2
30.00 g HF x              x            x
               20.01 g HF   2 mol HF     1 mol SnF2
       Additional Sample Problem #1
 Sodium peroxide reacts vigorously with water to produce
  sodium hydroxide and oxygen.

        2Na2O2(s) + 2H2O(g)               4NaOH(s) + O2(g)
          50.0 g                                         ?g


  a. What mass in grams of O2 is produced when 50.0 g of
    Na2O2 react?


                 1 mol Na2O2     1 mol O2   32.00 g O2   = 10.3 g O2
50.0 g Na2O2 x                x           x
                 77.98 g Na2O2 2 mol Na2O2 1 mol O2
       Additional Sample Problem #1
 Sodium peroxide reacts vigorously with water to produce
  sodium hydroxide and oxygen.

        2Na2O2(s) + 2H2O(g)              4NaOH(s) + O2(g)
          50.0 g          ?g


  b. What mass in grams of water is needed to react
    completely with the Na2O2?


                 1 mol Na2O2    2 mol H2O   18.02 g H2O =   11.5 g H2O
50.0 g Na2O2 x                x           x
                 77.98 g Na2O2 2 mol Na2O2 1 mol H2O
               Homework
HW 9-1,2
 pg. 285 Practice #1-2
 pg. 287 Practice #1-3
         Due: Friday 1/11

				
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