three trials. The mass of sodium carbonate was found by multiplying the moles of
sodium carbonate by its molar mass, which was calculated to be 0.0588 g, 0.0578
g and 0.0572 g, respectively. The percent of sodium bicarbonate in the unknown
sample was found by dividing the mass of sodium bicarbonate by the mass of the
unknown, then multiplying this result by 100 in order to obtain the percent. For
the three trials, the percents were 25.90%, 25.70% and 25.60%, respectively.
Finally, the average percent of sodium carbonate was found by adding all three
percents together, then dividing by three, yielding 25.7 for the experiment, and the
standard deviation was calculated using the given equation, which was calculated
to be 0.1581.

119.
Conclusion:
120.
In conclusion, it is confirmed that the goal of the experiment was
achieved, since three successful titrations were performed. These titrations
allowed for the students to calculate the percent of sodium carbonate found in the
unknown sample. The experiment was successful, because the standard deviation
was very small, indicting that minimal error had occurred. Another way to
confirm that the experiment was successful was by analyzing the qualitative
observations. Once the titrations turned the slightest bit of green, the titration was
considered at its endpoint, and the percent of sodium bicarbonate present in the
unknown could be found. The three percents obtained were at most 0.3% different
from each other, which is fairly well, because the percents also varied with the
weights of the unknown samples.
121.
Recommendations:
122.
The first recommendation that I have for this lab is to directly
specify that if during boiling, the solution is not turning back to blue, but is in fact
turning even more yellow than originally, the student should stop the boiling since
this would waste time. The second recommendation I have is that the procedure
should not say “boil for five minutes”, because most solutions did not take five
minutes, but rather three minutes at most to get the desired blue color. The
procedure should say to boil until the original blue color is restored.
123.
References:

124.
Chang. Determination of the Equilibrium Constant for Bromocresol Green
ments/6_EquilibriumConstant_Sp12.pdf (accessed Feb 24, 2017).
125.
Frostburg. Acid-Base Indicators
(accessed
Feb 24, 2017).
126.
Hendrickson, K. What Is Sodium Carbonate?
(accessed Feb
23, 2017).
127.