I need to figure out how to calculate the molar mass of this unknown acid by titration , and give some errors why the ideal molar mass was not obtained? Mass of acid used: 2.4060 grams Buret initial volume : 0.00mL End volume of buret: 99.4 mL [NaOH]=0.1501M unknown #122 : molar mass 152.15 g.mol for error analysis
I need to figure out how to calculate the molar mass of this unknown acid by titration , and give some errors why the ideal molar mass was not obtained? Mass of acid used: 2.4060 grams Buret initial volume : 0.00mL End volume of buret: 99.4 mL [NaOH]=0.1501M unknown #122 : molar mass 152.15 g.mol for error analysis
Chapter8: Sampling, Standardization, And Calibration
Section: Chapter Questions
Problem 8.2QAP
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I need to figure out how to calculate the molar mass of this unknown acid by titration , and give some errors why the ideal molar mass was not obtained?
Mass of acid used: 2.4060 grams
Buret initial volume : 0.00mL
End volume of buret: 99.4 mL
[NaOH]=0.1501M
unknown #122 : molar mass 152.15 g.mol for error analysis
![Experiment 1 Part B, Molar Mass of an Unknown Acid
1. Weigh a weighing boat and record its mass. Your unknown acid is in plastic sample bag. Write your
description of the sample including unknown number in your notebook. Your instructor will direct
you to the mass of the unknown acid that you need to weigh within +/- 0.005 grams of the sample size.
Transfer sample to 250 mL Erlenmeyer flask. Add about 50 mL of deionized water and 2-3 drops of
phenolphthalein to the sample in the flask. The acid may be relatively insoluble, so don't worry if it
doesn't all dissolve at first.
0.4M
2. Fill the buret with the previously standardized sodium hydroxide solution (make sure you note the
concentration and write it in your notebook for use in the calculations section of your report) and
record the level of the liquid in the buret to 0.01 mL.
C.
3. Titrate the acid to the end point. As the acid is neutralized by the base, it will tend to dissolve in the
solution. If your unknown is so insoluble that the phenolphthalein color persists before all the solid
dissolves, add about 25 mL of ethanol to the solution to increase the solubility. [This procedure does
not affect the results of the titration, only insures that all the unknown solid acid is dissolved in the
solution where it can react with the sodium hydroxide.] Then continue the titration. Record the
volume of liquid in the buret at the end point.
4. Prepare a second sample of your unknown and titrate as before.o du
Note: Waste instructions will be given by your instructor
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Transcribed Image Text:Experiment 1 Part B, Molar Mass of an Unknown Acid
1. Weigh a weighing boat and record its mass. Your unknown acid is in plastic sample bag. Write your
description of the sample including unknown number in your notebook. Your instructor will direct
you to the mass of the unknown acid that you need to weigh within +/- 0.005 grams of the sample size.
Transfer sample to 250 mL Erlenmeyer flask. Add about 50 mL of deionized water and 2-3 drops of
phenolphthalein to the sample in the flask. The acid may be relatively insoluble, so don't worry if it
doesn't all dissolve at first.
0.4M
2. Fill the buret with the previously standardized sodium hydroxide solution (make sure you note the
concentration and write it in your notebook for use in the calculations section of your report) and
record the level of the liquid in the buret to 0.01 mL.
C.
3. Titrate the acid to the end point. As the acid is neutralized by the base, it will tend to dissolve in the
solution. If your unknown is so insoluble that the phenolphthalein color persists before all the solid
dissolves, add about 25 mL of ethanol to the solution to increase the solubility. [This procedure does
not affect the results of the titration, only insures that all the unknown solid acid is dissolved in the
solution where it can react with the sodium hydroxide.] Then continue the titration. Record the
volume of liquid in the buret at the end point.
4. Prepare a second sample of your unknown and titrate as before.o du
Note: Waste instructions will be given by your instructor
0.17
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