Baking Soda/Vinegar Stoichiometry Lab

Materials

• 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• 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)

Use Stoichiometry to find liters of gas from grams of baking soda.

• Find the molecular weight of NaHCO3

• Use atomic weights:

• Na = _____

• H = _____

• C = _____

• O__x3 = ____

• Molecular weight of baking soda is ___g/mol

The Stoichiometry Math

____ g NaHCO3 x 1 mol NaHCO3

_____ g NaHCO3

___ mol CO2 x 22.4 liters =

___mol NaHCO3 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?