Find the error in this notebook entry and explain what the error is and how it c
ID: 791017 • Letter: F
Question
Find the error in this notebook entry and explain what the error is and how it can be corrected. What information is missing from the notebook that might have prevented the error?
Titration of 3 different acids using NaOH
Acids titrated:
benzoic acid, formula: C6H5COOH, molar mass: 122.12 g/mol
malonic acid, formula: HOOCCH2COOH, molar mass: 104.06 g/mol
acetic acid, formula: CH3COOH, molar mass: 60.05 g/mol
indicator used: thymol blue, color (acid=yellow, base=blue) endpoint color: green (changing from acid to base)
Problem: find the concentration of the NaOH solution by titrating these 3 acids
Data:
mass of acid used
(g)
moles of acid used
(moles)
moles of NaOH
(moles)
volume of NaOH
(at endpoint) (mL)
concentration of NaOH
(mol/L)
acidmass of acid used
(g)
moles of acid used
(moles)
moles of NaOH
(moles)
volume of NaOH
(at endpoint) (mL)
concentration of NaOH
(mol/L)
C6H5COOH 0.357 .00292 .00292 28.35 0.103 C6H5COOH 0.382 .00313 .00313 30.40 0.103 HOOCCH2COOH 0.349 .00335 .00335 65.12 0.0514 HOOCCH2COOH 0.328 .00315 .00315 61.23 0.0514 CH3COOH 0.188 .00313 .00313 30.37 0.103 CH3COOH 0.197 .00328 .00328 31.87 0.103Explanation / Answer
mass of acid used
(g)
moles of acid used
(moles)
moles of NaOH
(moles)
volume of NaOH
(at endpoint) (mL)
concentration of NaOH
(mol/L)
conc of NaOH for C6H5COOH acid= 0.00292/0.02835 = 0.1031M
error = 0.1031-0.103 = 0.0001
conc of NaOH for C6H5COOH = 0.00313/ 0.0304 =0.1029M
error = 0.103-0.1029 = 0.0001
conc of NaOH for HOOCCH2COOH= 0.00335/0.06512 =0.0514M
errror = 0
conc of NaOH for HOOCCH2COOH=0.00315/ 0.06123 =0.05144M
error = 0.05144-0.0514 = 0.0004
conc of NaOH for CH3COOH= 0.00313/0.03037 = 0.103M
error = 0
conc of NaOH for CH3COOH=0.00328/0.03187= 0.1029M
error = 0.103-0.1029 = 0.0001
to check the error the overall pH of the resultant solution should be measured and overall pH after complete completion of acid base reaction the pH should be 7.. the data pH is missing from the table..that also should be included..the error can be corrected by measuring the overall pH after completion of reaction ..if that is more than 7 then acid should be added and if less 7 base should be added
acidmass of acid used
(g)
moles of acid used
(moles)
moles of NaOH
(moles)
volume of NaOH
(at endpoint) (mL)
concentration of NaOH
(mol/L)
C6H5COOH 0.357 .00292 .00292 28.35 0.103 C6H5COOH 0.382 .00313 .00313 30.40 0.103 HOOCCH2COOH 0.349 .00335 .00335 65.12 0.0514 HOOCCH2COOH 0.328 .00315 .00315 61.23 0.0514 CH3COOH 0.188 .00313 .00313 30.37 0.103 CH3COOH 0.197 .00328 .00328 31.87 0.103Related Questions
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