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Lab: Determining a
Mole Ratio
Objective: Experimentally determine a mole ratio for a chemical reaction.
A. Write a balanced chemical equation for the reaction that takes place in this lab:
B. What is the theoretical mole ratio of NaHCO3 to NaCl?
C. Data Table
Mass (grams)
Test Tube #1
Test Tube #2
Test Tube #3
Empty test tube
Test tube + NaHCO3
NaHCO3
= After Heating =
Test tube + NaCl
NaCl
D. Calculations (Show all work using proper dimensional analysis, units, and sig figs.)
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Test tube 1
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mol NaHCO3 =
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mol NaCl =
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experimental mol ratio =
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Test tube 2
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mol NaHCO3 =
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mol NaCl =
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experimental mol ratio =
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Test tube 3
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mol NaHCO3 =
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mol NaCl =
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experimental mol ratio =
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Average mole ratio (show work!)
If your work is not neat and legible, you will be asked to redo this worksheet!
(If you’d like to do it over, more neatly, you can download a new copy from our on-line lesson calendar.)
LAB PROCEDURES: DETERMINING A MOLE
In this experiment, you will react baking soda (NaHCO3) with hydrochloric acid (HCl)
and produce salt (NaCl). You will determine the moles of reactant used and product
produced through careful measurement of masses and by dividing by the appropriate
formula weights.
MATERIALS
sodium bicarbonate (NaHCO3)
3 M hydrochloric acid (HCl)
18 x 150 mm or larger test tubes (3)
PROCEDURE
1. Label three 18 x 150 mm test tubes (#1, #2, #3).
2. Measure and record in the data table the masses of each of the labeled test tubes
to the nearest hundredth of a gram.
3. Add to each test tube just enough baking soda to fill the curved bottom of the test
tube.
4. Measure and record in the table the masses of each respective tube with baking
soda.
5. Determine the mass of baking soda in each test tube. If necessary, adjust the
mass of baking soda so that it is greater than 0.25 grams, but not more than 0.50
grams.
6. To test tube #1, add 3 M HCl one drop at a time, allowing the drop to run down the
inside wall of the test tube. Listen and watch the reaction. Gently agitate the tube
after each drop until the reaction stops. Continue to add drops until there is no
evidence of any further reaction.
7. Repeat the procedures in step #6 with test tubes #2 and #3.
8. Evaporate off the fluid in each test tube by gentle heating above the bunsen
burner flame, slowly circling in and out of the heat. There must be no eruption of
fluid out of your test tube. Proceed until dry.
Caution: Make sure that the open end of the test tube is
not pointed at anyone!
9. Remove the test tube from the flame and test for water vapor by inverting a clean,
dry test tube over the mouth of your test tube. If you see condensation, continue
the drying procedure for an additional five minutes and test again. When
condensation can no longer be seen, place the test tube to one side and allow it to
cool for at least 5 minutes before taking its mass.
10. Perform steps #8 and #9 for test tubes #2 and #3.
11. Measure and record the mass for each test tube.
12. Return all materials, clean up your lab area, sink, and wash your hands.