With the information from my pictures please help me with the following: 1. Volume at Equivalence Point_______ 2. Volume at one-half Equivalence Point _________ 3. pKa________ 4. Ka_________ 5. Average Ka (show Calculations)_________ 6. Standard Deviation of Ka _________

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ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
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With the information from my pictures please help me with the following:
1. Volume at Equivalence Point_______
2. Volume at one-half Equivalence Point _________
3. pKa________
4. Ka_________
5. Average Ka (show Calculations)_________
6. Standard Deviation of Ka _________

If I need to I will post 6 different posts.


**Determination of the Dissociation Constant of a Weak Acid**

### C. Determination of pKa of Unknown Acid

#### First Determination
| mL NaOH | pH  |
|---------|-----|
| 0       | 3.5 |
| 1       | 3.8 |
| 2       | 4.0 |
| 3       | 4.1 |
| 4       | 4.2 |
| 5       | 4.3 |
| 6       | 4.4 |
| 7       | 4.5 |
| 8       | 4.6 |
| 9       | 4.7 |
| 10      | 4.8 |
| 11      | 4.8 |
| 12      | 4.9 |
| 13      | 5.0 |
| 14      | 5.1 |
| 15      | 5.3 |
| 16      | 5.4 |
| 17      | 5.2 |
| 18      | 5.3 |
| 19      | 5.4 |
| 20      | 5.6 |
| 21      | 5.8 |
| 22      | 5.8 |
| 23      | 9.8 |
| 24      | 10.2|
| 25      | 10.8|
| 26      | 11.3|
| 27      | 11.4|
| 28      | 11.5|
| 29      | 11.6|
| 30      | 11.8|

#### Second Determination

| mL NaOH | pH  |
|---------|-----|
| 31      | 11.8|

#### Third Determination

| mL NaOH | pH  |
|---------|-----|
|         |     |

#### Additional Parameters Calculated

* Volume at equivalence point: 22.10 mL
* Volume at one-half equivalence point: 11.05 mL

|             | pK<sub>a</sub> | K<sub>a</sub> |
|-------------|----------------|---------------|
| First       |                |               |
| Second      |                |               |
| Third       |                |               |
| Average
Transcribed Image Text:**Determination of the Dissociation Constant of a Weak Acid** ### C. Determination of pKa of Unknown Acid #### First Determination | mL NaOH | pH | |---------|-----| | 0 | 3.5 | | 1 | 3.8 | | 2 | 4.0 | | 3 | 4.1 | | 4 | 4.2 | | 5 | 4.3 | | 6 | 4.4 | | 7 | 4.5 | | 8 | 4.6 | | 9 | 4.7 | | 10 | 4.8 | | 11 | 4.8 | | 12 | 4.9 | | 13 | 5.0 | | 14 | 5.1 | | 15 | 5.3 | | 16 | 5.4 | | 17 | 5.2 | | 18 | 5.3 | | 19 | 5.4 | | 20 | 5.6 | | 21 | 5.8 | | 22 | 5.8 | | 23 | 9.8 | | 24 | 10.2| | 25 | 10.8| | 26 | 11.3| | 27 | 11.4| | 28 | 11.5| | 29 | 11.6| | 30 | 11.8| #### Second Determination | mL NaOH | pH | |---------|-----| | 31 | 11.8| #### Third Determination | mL NaOH | pH | |---------|-----| | | | #### Additional Parameters Calculated * Volume at equivalence point: 22.10 mL * Volume at one-half equivalence point: 11.05 mL | | pK<sub>a</sub> | K<sub>a</sub> | |-------------|----------------|---------------| | First | | | | Second | | | | Third | | | | Average
### Determination of the Dissociation Constant of a Weak Acid

#### Titration Curve

This graph represents the titration curve which is used to determine the dissociation constant (Ka) of a weak acid. The horizontal axis indicates the volume of NaOH (sodium hydroxide) added in milliliters (mL), ranging from 0 to 36 mL. The vertical axis shows the pH levels, which range from 1 to 14.

#### Key Observations:
1. **Initial pH**: The titration starts with an acidic solution at a pH of approximately 3.
2. **pH Increase**: As NaOH is added, the pH gradually increases.
3. **Equivalence Point**: There is a sharp increase in pH around the addition of 16-20 mL of NaOH, indicating the equivalence point where the amount of NaOH is stoichiometrically equivalent to the amount of acid.
4. **Post Equivalence**: After the equivalence point, the pH levels off and increases more gradually as more NaOH is added, stabilizing around a pH of 11-12.
5. **Buffer Region**: The region before the equivalence point where the pH rises steadily indicates the buffer region of the weak acid and its conjugate base.

This data is essential in determining the dissociation constant, Ka, of the weak acid using the Henderson-Hasselbalch equation at the midpoint (half-equivalence point) of the titration where pH = pKa. 

The graph is copyrighted © 2018 Pearson Education, Inc.

### Educational Significance
Understanding titration curves is crucial for chemistry students as it provides insight into the behavior of acids, bases, and buffering solutions. The analysis of such graphs helps in calculating important properties like pKa and understanding the strength and dissociation behavior of weak acids.
Transcribed Image Text:### Determination of the Dissociation Constant of a Weak Acid #### Titration Curve This graph represents the titration curve which is used to determine the dissociation constant (Ka) of a weak acid. The horizontal axis indicates the volume of NaOH (sodium hydroxide) added in milliliters (mL), ranging from 0 to 36 mL. The vertical axis shows the pH levels, which range from 1 to 14. #### Key Observations: 1. **Initial pH**: The titration starts with an acidic solution at a pH of approximately 3. 2. **pH Increase**: As NaOH is added, the pH gradually increases. 3. **Equivalence Point**: There is a sharp increase in pH around the addition of 16-20 mL of NaOH, indicating the equivalence point where the amount of NaOH is stoichiometrically equivalent to the amount of acid. 4. **Post Equivalence**: After the equivalence point, the pH levels off and increases more gradually as more NaOH is added, stabilizing around a pH of 11-12. 5. **Buffer Region**: The region before the equivalence point where the pH rises steadily indicates the buffer region of the weak acid and its conjugate base. This data is essential in determining the dissociation constant, Ka, of the weak acid using the Henderson-Hasselbalch equation at the midpoint (half-equivalence point) of the titration where pH = pKa. The graph is copyrighted © 2018 Pearson Education, Inc. ### Educational Significance Understanding titration curves is crucial for chemistry students as it provides insight into the behavior of acids, bases, and buffering solutions. The analysis of such graphs helps in calculating important properties like pKa and understanding the strength and dissociation behavior of weak acids.
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