Name: __________________________
Section: _____
Date: _______________
Lab Partner: _____________________
Baking Soda Stoichiometry
Prelab Questions
Baking soda (sodium bicarbonate is a common ingredient in baked goods. What is the
formula for sodium bicarbonate? What state of matter is sodium bicarbonate?
When baking soda is heated, it breaks down into new compounds. This is an example of
what kind of reaction?
If you omit baking soda from a recipe, the final product’s texture isn’t as light and fluffy
as you would expect it to be. What does that tell you about the state of at least one of the
products from the reaction?
Background
In this experiment, you will use stoichiometry to determine which of the three reactions
takes place when baking soda is heated.
1. Sodium bicarbonate  sodium hydroxide + carbon dioxide
2. Sodium bicarbonate  sodium oxide + carbon dioxide + water
3. Sodium bicarbonate  sodium carbonate + carbon dioxide + water
Before completing the experiment, determine the complete balanced equation for each of
the possible reactions above, including the states of each compound involved.
1.
2.
3.
Materials
Sodium bicarbonate
Bunsen burner
Ring stand
Iron ring
Clay triangle
Balance
Crucible
Crucible tongs
Procedure
1. Make sure the crucible is clean and dry.
2. Use the balance to find the exact mass of the crucible. Record the mass in the data
table.
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3. Place about 2 grams of baking soda in the crucible, and weigh the crucible
containing the baking soda on the balance. Be sure to record the exact mass you
obtain. Do not zero the balance with the empty crucible on it—you need to know
the total mass of the crucible with the baking soda in it.
4. Heat the crucible with the Bunsen burner for about 10 min. You can use a stirring
rod or spatula to stir the powder and break up any clumps that form.
5. Remove the crucible from the heat and allow it to cool. When it is cool to the touch,
find the mass of the crucible and the solid in it. Record this mass.
6. When you are finished, wash the contents down the sink with lots of water. Clean
and dry the crucible and any other equipment you used.
7. Data
Material(s)
1. Empty crucible
Mass (g)
2. Crucible with baking soda
(before heating)
3. Mass of baking soda (subtract
line 1 from line 2)
4. Mass of crucible with solid in it
(after heating)
5. Mass of solid (subtract line 4
from line 1)
Calculations
1. From the background, what are the three possible reactions you could have witnessed
in this experiment?
1.
2.
3.
2. Calculate the number of moles of baking soda you started with. Show your work!
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3. For each reaction equation in question 1, calculate what mass of solid product you
would expect to have after decomposing the sodium bicarbonate. Show your work,
including the mole ratios you used!
1.
2.
3.
4. Compare the results of your calculations to the mass of the solid in your data table.
According to your data, which equation properly expresses how baking soda
decomposes?
5. Check with your teacher to find the actual reaction that took place. Were you correct?
If not, what do you think went wrong?
6. You probably didn’t get exactly the same amount of solid as you calculated. Find your
percent difference using this equation:
predicted grams of solid-actual grams of solid
percent difference=
×100
predicted grams of solid
7. Did you get more or less than what your calculations predicted? What are some
possible reasons for the difference?
Conclusion
What did you learn from this experiment?
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