Chem 1332
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- Words: 714
- Pages: 4
View Attempt
https://scholar.uh.edu/webct/ViewStudentAttempt.dowebct?attempt=1777...
View Attempt 2 of unlimited Title:
Chapter 19(1)
Started:
November 8, 2009 6:55 PM
Submitted:
November 8, 2009 7:41 PM
Time spent:
00:46:16
Total score: 8/12 = 66.67% 1.
Total score adjusted by 0.0
Maximum possible score: 12
Buffer Synthesis 5 Match the acid/base pair that is suitable for preparing a buffer of each given approximate concentration. You will need to refer to Tables in the book of weak acids and bases and polyprotic acid
C6H5NH2/ C6H5NH3Cl
[H3O+] = 10-4
NaH2AsO3/Na2HAsO3
[H3O+] = 10-9
NH3/NH4Cl
[H3O+] = 10-7
Statement
Response
Value
C6H5NH2/ C6H5NH3Cl
[H3O+] = 10-7
Incorrect [H3O+] = 10-4
NaH2AsO3/Na2HAsO3
[H3O+] = 10-4
Incorrect [H3O+] = 10-7
NH3/NH4Cl
[H3O+] = 10-9
Correct
Score:
2.
Correct Match
[H3O+] = 10-9
0/1
Indicator 5 Which indicator would be the best to use for a titration between 0.10 M HF with 0.10 M NaOH? You will probably need to consult the appropriate table in the book.
Student Response
Value
Correct Answer
Feedback
1. thymol blue, 100% color change at pH 8-10 2. bromothymol 0% blue, color change at pH 6-8 3. methyl red, 0% color change at pH 3-5
1 of 4
08-Nov-09 7:43 PM
View Attempt
https://scholar.uh.edu/webct/ViewStudentAttempt.dowebct?attempt=1777...
4. alizarin 0% yellow R, color change at pH 10-12 5. methyl 0% violet, , color change at pH 0-2 Score:
3.
1/1
Chapter 11 Simple Buffer 5 Calculate the pH of a solution that is 0.090 M HBrO and 0.026 M NaBrO. Ka of HBrO is 2.0 x 10-9.
Student Response Answer 9.24 Score:
4.
Value
Correct Answer
0%
8.16
0/1
Chapter 11 Buffer MV 4 Calculate the pH of a solution that results from mixing 30.8 mL of 0.166 M acetic acid with 18.9 mL of 0.100 M sodium acetate. The Ka value for CH3COOH is 1.8 x 10-5.
Student Response Answer 1.47 Score:
5.
Value
Correct Answer
0%
4.31
0/1
Buffer Ratio 1 What is the buffer component ratio, ([CH3CH2COO-]/[CH3CH2COOH]) of a propanoate buffer that has a pH of 5.80. Ka of CH3CH2COOH is 1.3 x 10-5.
Student Response Answer 8.2 Score:
6.
2 of 4
Value
Correct Answer
100%
8.13
1/1
Additions to Buffer 41
08-Nov-09 7:43 PM
View Attempt
https://scholar.uh.edu/webct/ViewStudentAttempt.dowebct?attempt=1777...
A buffer is prepared by mixing 122 mL of 0.232 M HCl with 756 mL of 0.545 M sodium acetate (NaCH3COO). Given that the Ka of acetic acid is 1.8 x 10-5, calculate the pH of the solution.
Student Response Answer not answered Score:
7.
Value
Correct Answer
0%
5.88
0/1
Chapter 11 Titrations SS 6 Calculate the pH during the titration of 20.0 mL of 0.25 M HCl(aq) with 0.25 M NaOH(aq) after 20.27 mL of the base have been added.
Student Response Answer 11.2 Score:
8.
Value
Correct Answer
100%
11.22
1/1
Chapter 11 Titrations WS 26 Calculate the pH during the titration of 20.00 mL of 0.1000 M HNO2(aq) with 0.1000 M NaOH(aq) after 20.13 mL of the base have been added. Ka of nitrous acid = 4.3 x 10-4.
Student Response Answer 10.5 Score:
9.
Value
Correct Answer
100%
10.51
1/1
Titration WS 4 Calculate the pH during the titration of 20.00 mL of 0.1000 M CH3CH2CH2COOH with 0.1000 M NaOH after 24.6 mL of the base have been added. Ka of butanoic acid = 1.54 x 10-5.
Student Response Answer 12 Score:
Value
Correct Answer
100%
12.01
1/1
10. Equivalence Point 2
3 of 4
08-Nov-09 7:43 PM
View Attempt
https://scholar.uh.edu/webct/ViewStudentAttempt.dowebct?attempt=1777...
Using Tables from the book when needed, determine the volume of 0.937 M NaOH needed to reach the first equivalence point in the titration of 24.5 mL of 0.229 M H2CO3.
Student Response Answer 5.99 Score:
Value
Correct Answer
100%
6.0
1/1
11. Chapter 11 Titrations EPP WS 10 Determine the pH at the equivalence (stoichiometric) point in the titration of 44.0 mL of 0.570 M HCOOH by 0.710 M NaOH. The Ka of HCOOH is 1.8 x 10-4.
Student Response Answer 8.62 Score:
Value
Correct Answer
100%
8.62
1/1
12. Chapter 11 Titrations HEP SW 1 What is the volume in mL of 0.957 M HCl(aq) needed to reach halfway to the equivalence (stoichiometric) point in the titration of 36.7 mL of 0.933 M NH3(aq).
Student Response Answer 17.9 Score:
Value
Correct Answer
100%
17.9
1/1
Done
4 of 4
08-Nov-09 7:43 PM
https://scholar.uh.edu/webct/ViewStudentAttempt.dowebct?attempt=1777...
View Attempt 2 of unlimited Title:
Chapter 19(1)
Started:
November 8, 2009 6:55 PM
Submitted:
November 8, 2009 7:41 PM
Time spent:
00:46:16
Total score: 8/12 = 66.67% 1.
Total score adjusted by 0.0
Maximum possible score: 12
Buffer Synthesis 5 Match the acid/base pair that is suitable for preparing a buffer of each given approximate concentration. You will need to refer to Tables in the book of weak acids and bases and polyprotic acid
C6H5NH2/ C6H5NH3Cl
[H3O+] = 10-4
NaH2AsO3/Na2HAsO3
[H3O+] = 10-9
NH3/NH4Cl
[H3O+] = 10-7
Statement
Response
Value
C6H5NH2/ C6H5NH3Cl
[H3O+] = 10-7
Incorrect [H3O+] = 10-4
NaH2AsO3/Na2HAsO3
[H3O+] = 10-4
Incorrect [H3O+] = 10-7
NH3/NH4Cl
[H3O+] = 10-9
Correct
Score:
2.
Correct Match
[H3O+] = 10-9
0/1
Indicator 5 Which indicator would be the best to use for a titration between 0.10 M HF with 0.10 M NaOH? You will probably need to consult the appropriate table in the book.
Student Response
Value
Correct Answer
Feedback
1. thymol blue, 100% color change at pH 8-10 2. bromothymol 0% blue, color change at pH 6-8 3. methyl red, 0% color change at pH 3-5
1 of 4
08-Nov-09 7:43 PM
View Attempt
https://scholar.uh.edu/webct/ViewStudentAttempt.dowebct?attempt=1777...
4. alizarin 0% yellow R, color change at pH 10-12 5. methyl 0% violet, , color change at pH 0-2 Score:
3.
1/1
Chapter 11 Simple Buffer 5 Calculate the pH of a solution that is 0.090 M HBrO and 0.026 M NaBrO. Ka of HBrO is 2.0 x 10-9.
Student Response Answer 9.24 Score:
4.
Value
Correct Answer
0%
8.16
0/1
Chapter 11 Buffer MV 4 Calculate the pH of a solution that results from mixing 30.8 mL of 0.166 M acetic acid with 18.9 mL of 0.100 M sodium acetate. The Ka value for CH3COOH is 1.8 x 10-5.
Student Response Answer 1.47 Score:
5.
Value
Correct Answer
0%
4.31
0/1
Buffer Ratio 1 What is the buffer component ratio, ([CH3CH2COO-]/[CH3CH2COOH]) of a propanoate buffer that has a pH of 5.80. Ka of CH3CH2COOH is 1.3 x 10-5.
Student Response Answer 8.2 Score:
6.
2 of 4
Value
Correct Answer
100%
8.13
1/1
Additions to Buffer 41
08-Nov-09 7:43 PM
View Attempt
https://scholar.uh.edu/webct/ViewStudentAttempt.dowebct?attempt=1777...
A buffer is prepared by mixing 122 mL of 0.232 M HCl with 756 mL of 0.545 M sodium acetate (NaCH3COO). Given that the Ka of acetic acid is 1.8 x 10-5, calculate the pH of the solution.
Student Response Answer not answered Score:
7.
Value
Correct Answer
0%
5.88
0/1
Chapter 11 Titrations SS 6 Calculate the pH during the titration of 20.0 mL of 0.25 M HCl(aq) with 0.25 M NaOH(aq) after 20.27 mL of the base have been added.
Student Response Answer 11.2 Score:
8.
Value
Correct Answer
100%
11.22
1/1
Chapter 11 Titrations WS 26 Calculate the pH during the titration of 20.00 mL of 0.1000 M HNO2(aq) with 0.1000 M NaOH(aq) after 20.13 mL of the base have been added. Ka of nitrous acid = 4.3 x 10-4.
Student Response Answer 10.5 Score:
9.
Value
Correct Answer
100%
10.51
1/1
Titration WS 4 Calculate the pH during the titration of 20.00 mL of 0.1000 M CH3CH2CH2COOH with 0.1000 M NaOH after 24.6 mL of the base have been added. Ka of butanoic acid = 1.54 x 10-5.
Student Response Answer 12 Score:
Value
Correct Answer
100%
12.01
1/1
10. Equivalence Point 2
3 of 4
08-Nov-09 7:43 PM
View Attempt
https://scholar.uh.edu/webct/ViewStudentAttempt.dowebct?attempt=1777...
Using Tables from the book when needed, determine the volume of 0.937 M NaOH needed to reach the first equivalence point in the titration of 24.5 mL of 0.229 M H2CO3.
Student Response Answer 5.99 Score:
Value
Correct Answer
100%
6.0
1/1
11. Chapter 11 Titrations EPP WS 10 Determine the pH at the equivalence (stoichiometric) point in the titration of 44.0 mL of 0.570 M HCOOH by 0.710 M NaOH. The Ka of HCOOH is 1.8 x 10-4.
Student Response Answer 8.62 Score:
Value
Correct Answer
100%
8.62
1/1
12. Chapter 11 Titrations HEP SW 1 What is the volume in mL of 0.957 M HCl(aq) needed to reach halfway to the equivalence (stoichiometric) point in the titration of 36.7 mL of 0.933 M NH3(aq).
Student Response Answer 17.9 Score:
Value
Correct Answer
100%
17.9
1/1
Done
4 of 4
08-Nov-09 7:43 PM
