(a) How did the mL of titrant needed to reach the endpoint using the indicator y
ID: 521298 • Letter: #
Question
(a) How did the mL of titrant needed to reach the endpoint using the indicator you chose (Part 3) compare with the mL of titrant needed to reach the equivalence point (Part 2)?
(b) What does this say about these two methods? Is one a better means of monitoring a titration than the other? Why or why not?
PART 2
PART 3
Table 1: Indicator Ranges, Color observations and Neutralization Data Color Change Color Change Final PART1 pH Range Initial Beaker 1 (bromothymol blue) 3.55-4.05pH blue Clear Beaker 2 (tumeric) 8.23-4.25pH Dark Orange Yelow pink Beaker 3 (mehyl orange) 8.32-3.13 pH Orange Part 2 Moles of ml Citric Acid needed for Neutralization Citric Acid Neutralization Used pH 7pH 11.57 0.50mlExplanation / Answer
a) The equivalence point of a titration is defined as the volume of titrant required so that the amount of the titrant is stoichiometrically equal to the amount of the titre. The amount of the titre and the titrant are expressed in moles. Hence, we define the equivalence point of a titration as the volume of titrant where
moles of titrant added = moles of titre present in the titration system.
The end point of a titration is the volume of the titrant where the indicator shows a distinct color change. In case of the methyl orange indicator given in the data table, the indicator is orange in the titre (ammonia). As the titrant (citric acid) is added, neutralization of ammonia takes place at the equivalence point, the amount of the titre and the titrant are equal. When a slight excess of the titrant (citric acid), usually one drop extra, is added to the titration system, the indicator shows a sharp color change. This is the end point of the titration. In this case, methyl orange shows a dark pink color when a slight excess of citric acid is added.
Therefore, the mL (volume) of titrant needed to reach the end point is slightly greater than the mL (volume) of titrant required to reach the equivalence point.
b) What are the two methods that we are comparing?
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