Another day, another lab! Most recently, we observed a small scale reaction that involved baking soda and vinegar. This combination of acetic acid and sodium bicarbonate resulted in the production of sodium acetate, water, and carbon dioxide, as explained by the balanced equation below.
HC2H3O2(aq) + NaHCO3 (s) –> NaC2H3O2(aq) + CO2(g) + H2O(l)
We performed multiple repetitions of the experiment, using two fingers of vinegar with varying amounts of baking soda, ranging from .25 to 4.00 grams. Using this technique, we discovered that the limiting reactant changed from vinegar to baking soda as the amount of baking soda used increased. With lighter masses, there was not enough baking soda to react with all of the vinegar, and with heavier masses, there was not enough vinegar to dissolve the baking soda. This corresponds to our graph, which exhibits the plateau in CO2 production due to lack of vinegar. The section prior to the constant amount of CO2 production shows the masses at which all baking soda reacted. This change in limiting reactant is due to the molar ratio from the balanced equation. The mole to mole ratio is what determines the possible amount of substances produced, or in this case, carbon dioxide production.
The point of this lab was to review limiting reactants and stoichiometry. Using the mass of the substances prior to reaction, it is possible to calculate the theoretical number of grams produced by utilizing stoich, therefore verifying the results of the experiment.