Mass and Mole Relationships in a Chemical Reaction

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					       Mass and Mole Relationships in a Chemical Reaction

INTRODUCTION:

    In this experiment, you will measure the mass of the solid reactant, NaHCO3, and that of
    the solid product, NaCl. The experimental determination of these relative masses will
    enable you to determine the relative number of moles of this reactant and product. As a
    result of your observations and calculations, you will be able to determine the mass and
    mole relationships of the solid reactant and product.


PURPOSE:




MATERIALS:         - hydrochloric acid, 3M HCl                   - evaporating dish
                   - sodium bicarbonate, NaHCO3                  - watch glass
                   - eyedropper                                  - balance


PROCEDURE:

    1. Clean and dry an evaporating dish and a watch glass.

    2. Measure to the nearest 0.001g, the mass of the dish with watch glass.

    3. Place approximately 2-3 grams of sodium bicarbonate in the dish. Record the mass of

       the dish, sodium bicarbonate, and watch glass together.

    4. Slowly add about 10 mL of hydrochloric acid to the sodium bicarbonate in the

       evaporating dish. Then, carefully add hydrochloric acid from the eyedropper, drop by

       drop, until all signs of reaction have stopped.

       CAUTION: Hydrochloric acid is caustic and corrosive. Avoid contact with skin and
          eyes. Avoid breathing vapors. Make sure that you are wearing safety goggles
         and a lab apron. If any acid should spill on you, immediately flush the area with
         water and notify teacher.

    5. Set up your apparatus to heat the evaporating dish and contents (see Figure).
       6. Transfer the evaporating dish to your heating apparatus. Heat the evaporating dish

          slowly and attempt to avoid any splattering of the chemicals.

       7. When the volume of liquid in the dish is reduced and solid crystals begin to appear,

          reduce the heat to a low flame. Continue to heat until the contents of the evaporating

          dish appear to be completely dry. If the material begins to “pop”, you are heating too

          rapidly. When you have finished heating, remove the dish from the apparatus and let

it                cool for 15 minutes on a cooling pad.

       8. Weigh and record the mass of the watch glass, evaporating dish, and contents in the

          data chart.

                                          DATA TABLE

Mass of evaporating dish and watch glass
Mass of dish, glass, and NaHCO3
Mass of dish, glass, and residue (NaCl)



                                      CALCULATIONS

1. Calculate the mass of the reactant, NaHCO3.




2. Calculate the number of moles of NaHCO3 used.
3. Calculate the mass of the product, NaCl.




4. Calculate the moles of NaCl produced.




5. Calculate the experimental mole ratio of NaCl to NaHCO3.




6. Assuming the products are NaCl, CO2, and H2O, write a balanced equation for the reaction in

this experiment.
7. Using the reaction balanced in #6, determine the theoretical mole ration of NaCl to NaHCO3.




8. Determine the percentage error for your experimental mole ratio of NaHCO3 and NaCl.




9. Determine the percent yield for your reaction.