Transcript Baking Soda/Vinegar Stoichiometry Lab

Baking Soda/Vinegar
Stoichiometry Lab
Materials
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Balance
Weighing Paper
1 teaspoon of Baking Soda
1 small bottle of vinegar
1 zip lock plastic bag
Very large beaker of water
Procedure
• Fold weighing paper. Mass it on balance.
• Put one teaspoon of baking soda in the
weighing paper. Mass it.
• Subtract the two values to find the mass of
the baking soda.
• Fill the small bottle with vinegar, cap.
• Put baking soda and vinegar bottle in
plastic bag.
• Empty bag of as much air as possible,
seal shut, mass on balance.
• Estimate the amount of volume of bag.
Procedure Continued
• With Bag sealed, open bottle of vinegar.
• Re-mass the bag. Account for any difference in
mass from beginning to end.
• Use large beaker with water to estimate the new
volume of the bag.
• Clean up bottle for next class to use.
• Throw away plastic bag.
• Make sure equation is balanced.
• Figure out what volume of gas was supposed to
have been produced using stoichiometry
Observations
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Mass of weighing paper ___
Mass of baking soda plus paper ___
Mass of baking soda ___
Volume of bag before vinegar was opened ___
Mass of bag before opening vinegar ___
Mass of bag after opening vinegar ___
Volume of bag after vinegar opened ___
Estimated volume of gas produced ___
Balanced equation for reaction____
Full stoichiometry problem for figuring volume
of gas.____
Equation
___NaHCO3(s) + ___CH3COOH(l)
___CH3COONa(aq) + ___H2O(l) +
___CO2(g)
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Use Stoichiometry to find liters of
gas from grams of baking soda.
• Find the molecular weight of NaHCO3
• Use atomic weights:
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Na = _____
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H = _____
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C = _____
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O__x3 = ____
• Molecular weight of baking soda is ___g/mol
The Stoichiometry Math
____ g NaHCO3 x
___ mol CO2
___mol NaHCO3
1 mol NaHCO3
_____ g NaHCO3
x
22.4 liters
=
1 mol any gas
= ____ liters of CO2 gas
Questions
1) Give two reasons why it is difficult to get
an accurate reading of the volume of the
plastic bag before and after.
2) Give some reasons why you didn’t get
the volume of CO2 gas that you
expected from the stoichiometry math.
Questions II
• Why should the weight, before and after
the vinegar bottle is opened, be the same?
• Give a reason why the mass might have
changed, even though it shouldn’t.
• Give two reasons why might this baking
soda reaction might be good to use in
your sinks monthly to keep your home
plumbing from clogging up?
Extra
• What are some ways to improve this
experiment?
• What are some additional questions that
could be asked for this experiment?