Raising Dough
Every cake you’ve ever had, all the bread you’ve ever eaten (and most of the cookies) depend on a single ingredient that’s not even contained in the final product! That ingredient is carbon dioxide, CO2. Carbon dioxide can be formed in two basic ways: adding an acid to sodium hydrogen carbonate (AKA baking soda), or letting yeast organisms ferment. In this lab, we’ll be dealing with the former.
A baker must be careful to add just the right amount of baking soda to a recipe. Too little, and the cake doesn’t raise enough. Too much, and the cake is bitter tasting and crumbly. How do you know just how much to add? Stoichiometry!
Here is the problem you must solve: how much baking soda must be used to provide 425 mL of carbon dioxide under laboratory conditions? This is the amount required to raise up one layer cake. The density of carbon dioxide at oven temperature is 1.25 g/L.
Measure the mass of a clean, dry beaker and watch glass cover.
Add 1.0 - 1.5 grams of NaHCO3 to the beaker. Get the mass again (don’t forget the watch glass).
Slowly add ~10 mL of acetic acid to the beaker. Wait for the foaming to subside after each addition.
Following the technique outlined in class, add small amounts of acetic acid until the reaction is complete.
Gently heat the beaker, with cover. You want a slow simmer here, not a full boil.
When the liquid is reduced to a small amount of liquid mixed in with a lot of solids, stop. Wait five minutes. If any liquid remains, heat a little longer. DO NOT allow your product to get brown or black!
When the beaker has cooled enough to handle safely, obtain your final mass. Don’t forget the watch glass!
Your data section must contain all your raw data.
Your calculation section must include a balanced chemical equation, including all states of matter, and the molar masses of each product and reactant. Remember, equations and tables do not need to be WP’d.
Your calculation section must also include the actual, theoretical, and percent yields for this reaction. Be sure to show all your work!
Your conclusion must contain the answer to the problem posed above. Be sure to include a short discussion of limiting and excess reagents in this lab.
Your lab plan must contain a purpose, procedure, and a data TABLE. If all three of these items are not present, your lab plan will not be stamped.