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Exam 3 Questions for Solution - Elementary Quantitative Analysis | CHEM 221, Exams of Chemistry

University of Nebraska–Lincoln (UNL)Chemistry

Material Type: Exam; Class: Elementary Quantitative Analysis; Subject: Chemistry ; University: University of Nebraska - Lincoln; Term: Unknown 2007;

Typology: Exams

Pre 2010

Uploaded on 08/31/2009

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CHEMISTRY 221 - Dr. Powers Third Exam - FALL 2007
PRINT NAME ______________________________________________
(Last) (First) (MI)
ID# ___________________________
Signature ________________________________________
THIRD EXAM Lab Section______
November 20, 2007
BE SURE YOU HAVE 10 DIFFERENT PAGES OF THIS EXAM
**********WRITE YOUR NAME ON EVERY PAGE****************
SHOW ALL WORK - NO WORK - NO CREDIT
REPORT ALL ANSWERS WITH CORRECT LABELS AND SIGNIFICANT FIGURES
• All Cell phones must be turned off and cannot be used as a calculator.
• You may use a calculator, and an exam data sheet.
• Raise your hand if you have a question.
• Keep your eyes on your own paper.
• Several exam forms may be in use. It is a code violation if data from another exam form appears
on your paper.
• Keep all REQUIRED exams as part of your records.
REQUEST FOR REGRADE _______________Date
EXAMS SUBMITTED FOR REGRADES SHOULD NOT LEAVE THE RESOURCE CENTER!
Please regrade question because___________________________________________
_________________________________________________________________________
_________________________________________________________________________
Please regrade question because __________________________________________
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Please regrade question because __________________________________________
_________________________________________________________________________
______ Check here if there is a mistake in addition.
You must sign your regrade request, or it will not be considered a valid request.
I accept responsibility for all answers contained herein. ________________________________
Signature
When submitting regrade request, do not write on exam pages. Additional questions or comments are to
be placed on a separate sheet of paper and turned in with your test. Sign these as well.
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Download Exam 3 Questions for Solution - Elementary Quantitative Analysis | CHEM 221 and more Exams Chemistry in PDF only on Docsity!

CHEMISTRY 221 - Dr. Powers Third Exam - FALL 2007

PRINT NAME ______________________________________________

(Last) (First) (MI)

ID# ___________________________

Signature ________________________________________

THIRD EXAM Lab Section ______

November 20, 2007

BE SURE YOU HAVE 10 DIFFERENT PAGES OF THIS EXAM

**********WRITE YOUR NAME ON EVERY PAGE****************

SHOW ALL WORK - NO WORK - NO CREDIT

REPORT ALL ANSWERS WITH CORRECT LABELS AND SIGNIFICANT FIGURES

  • All Cell phones must be turned off and cannot be used as a calculator.
  • You may use a calculator, and an exam data sheet.
  • Raise your hand if you have a question.
  • Keep your eyes on your own paper.
  • Several exam forms may be in use. It is a code violation if data from another exam form appears on your paper.
  • Keep all REQUIRED exams as part of your records. REQUEST FOR REGRADE _______________Date EXAMS SUBMITTED FOR REGRADES SHOULD NOT LEAVE THE RESOURCE CENTER!

Please regrade question because___________________________________________

_________________________________________________________________________

_________________________________________________________________________

Please regrade question because __________________________________________

_________________________________________________________________________

_________________________________________________________________________

Please regrade question because __________________________________________

_________________________________________________________________________

______ Check here if there is a mistake in addition. You must sign your regrade request, or it will not be considered a valid request. I accept responsibility for all answers contained herein. ________________________________ Signature When submitting regrade request, do not write on exam pages. Additional questions or comments are to be placed on a separate sheet of paper and turned in with your test. Sign these as well.

Question No. Possible Points Points Earned TA Initials

Total 100

USEFUL EQUATIONS

Monoprotic Weak Acid: Diprotic Weak acid: Isoionic point: Triprotic Weak acid: Debye-Hϋckel Equation:ckel Equation: Gas Constant : 8.314472 J/K.mol Faraday constant: 9.649x10^4 C/mol ^    ^       (^1305) 0 51 2 ^   

. z log 2 K K^2 4 ( 1 )(F)(K ) [ H ] a^ a a     (^)  K F K K F K K H w     1 [ ]^211 K F K K F K K H w     1 [ ]^121 K F K K F K K H w     1 [ ]^211 K F K K F K K H w     2 [ ]^232

  1. (20 points) Predict the pH at the equivalence points for the following acid-base titrations: a. ( 5 points ) 10 mL of 0.0250 M HNO 3 is titrated with 0.0125 M LiOH b. ( 5 points )10 mL of 0.0250 M Butanoic acid (pKa = 4.818) is titrated with 0.0125 M LiOH
  1. (20 points) 50 mL of 0.0333 M of 1-Naphthoic acid (pKa = 3.67) is titrated with 0.05 M NaOH a. ( 5 points ) What is the pH before any NaOH is added? b. ( 5 points ) What is the pH after 5 mL of NaOH has been added?

c. ( 5 points ) What volume of NaOH is required to obtain a pH of 3.67? d. ( 5 points ) What pH range would 1-Naphthoic acid and its conjugate base be a good buffer?

  1. ( 5 points ) What is the Isoelectric point of Carbonic acid (pKa1=4.818, pKa2=10.329)
  1. ( 4 points ) What two factors determine the relative steepness of an acid-base titration curve?
  2. Increasing steepness