# The mass of sodium carbonate was found by multiplying

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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.
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