Redox Titration of Hydrogen Peroxide by Potassium Permanganate
Redox titration of hydrogen peroxide by potassium permanganate titration
I. OBJECTIVE OF THE EXPERIMENTAL
The principle and operation of redox titration of hydrogen peroxide with potassium permanganate as a titrant to accurately determine the content of hydrogen peroxide.
Second, the experimental principle
Hydrogen peroxide ($H_2O_2 $) is reductive and can be oxidized by potassium permanganate ($KMnO_4 $) in an acidic medium. The reaction equation is as follows:
$2KMnO_4 + 5H_2O_2 + 3H_2SO_4 = K_2SO_4 + 2MnSO_4 + 8H_2O + 5O_2 ↑ $
This reaction is a self-indicator reaction. The color change of potassium permanganate itself can indicate the titration endpoint. During the titration process, the purple color of the $KMnO_4 $solution will gradually fade. When the titration end point is reached, a slight excess of $KMnO_4 $will make the solution appear reddish and do not fade within half a minute.
III. Experimental instruments and reagents
1. ** Instruments **: acid burette, conical bottle, pipette, volumetric bottle, measuring cylinder, beaker, etc.
2. ** Reagents **: $KMnO_4 $standard solution (known exact concentration), $H_2O_2 $sample, $H_2SO_4 $solution (3 mol/L).
IV. Experimental steps
1. ** $H_2O_2 $Dilution of the sample **
- Accurately pipette a volume of $H_2O_2 $sample with a pipette, place it in a volumetric flask, dilute it to the scale with water, and shake well.
2. ** Titration Operation **
- Accurately measure a volume of the diluted $H_2O_2 $solution with an acid burette and place it in a conical flask.
- Add an appropriate amount of $H_2SO_4 $solution to the conical flask to provide an acidic environment.
- Load the $KMnO_4 $standard solution into an acid burette, zero and record the initial reading.
- Start the titration and shake while dripping. Note that the titration speed is slow first and then fast. When approaching the end point, slow down until the solution is reddish and does not fade within half a minute. Record the reading of the $KMnO_4 $solution at the end point of titration.
3. ** Parallel experiment **
- Repeat the above titration operation 2-3 times to record the data of each experiment.
5. Data recording and processing
1. ** Data Record **
| Number of Experiments | $H_2O_2 $Solution Volume (mL) | $KMnO_4 $Initial Solution Reading (mL) | $KMnO_4 $Solution Endpoint Reading (mL) | $KMnO_4 $Solution Consumption Volume (mL) |
| :---: | :---: | :---: | :---: | :---: |
| 1 | | | | |
| 2 | | | | |
| 3 | | | | |
2 . ** Data Processing **
- According to the chemical reaction equation, $n (H_2O_2) =\ frac {5} {2} n (KMnO_4) $.
- from $c =\ frac {n} {V} $ ($c $is the amount concentration of the substance, $n $is the amount of the substance, $V $is the volume of the solution) to obtain:
$c (H_2O_2) =\ frac {\ frac {5} {2} c (KMnO_4) V (KMnO_4) } {V (H_2O_2) } $
where $c (KMnO_4) $is the concentration of $KMnO_4 $standard solution, $V (KMnO_4) $is the volume of the solution consumed $KMnO_4 $, and $V (H_2O_2) $is the volume of the solution taken $H_2O_2 $.
- Calculate the concentration of $H_2O_2 $in each experiment, and calculate the average value, while calculating the relative deviation, to test the precision of the experimental results.
6. Precautions
1. At the beginning of titration, the addition speed of the $KMnO_4 $solution should be slow, because the reaction rate is slow at the beginning. After generating a certain amount of $Mn ^ {2 +} $, due to the catalytic action of $Mn ^ {2 +} $, the reaction rate will be accelerated. At this time, the titration speed can be appropriately accelerated, but it still needs to be shaken while dripping.
2. The judgment of the titration end point should be accurate. If the reddish color does not fade within half a minute, it is the end point. If the color fades too fast, it means that the end point has not been reached, and the titr 3. During the experiment, attention should be paid to keeping the instrument clean and dry to avoid the introduction of impurities affecting the experimental results.
I. OBJECTIVE OF THE EXPERIMENTAL
The principle and operation of redox titration of hydrogen peroxide with potassium permanganate as a titrant to accurately determine the content of hydrogen peroxide.
Second, the experimental principle
Hydrogen peroxide ($H_2O_2 $) is reductive and can be oxidized by potassium permanganate ($KMnO_4 $) in an acidic medium. The reaction equation is as follows:
$2KMnO_4 + 5H_2O_2 + 3H_2SO_4 = K_2SO_4 + 2MnSO_4 + 8H_2O + 5O_2 ↑ $
This reaction is a self-indicator reaction. The color change of potassium permanganate itself can indicate the titration endpoint. During the titration process, the purple color of the $KMnO_4 $solution will gradually fade. When the titration end point is reached, a slight excess of $KMnO_4 $will make the solution appear reddish and do not fade within half a minute.
III. Experimental instruments and reagents
1. ** Instruments **: acid burette, conical bottle, pipette, volumetric bottle, measuring cylinder, beaker, etc.
2. ** Reagents **: $KMnO_4 $standard solution (known exact concentration), $H_2O_2 $sample, $H_2SO_4 $solution (3 mol/L).
IV. Experimental steps
1. ** $H_2O_2 $Dilution of the sample **
- Accurately pipette a volume of $H_2O_2 $sample with a pipette, place it in a volumetric flask, dilute it to the scale with water, and shake well.
2. ** Titration Operation **
- Accurately measure a volume of the diluted $H_2O_2 $solution with an acid burette and place it in a conical flask.
- Add an appropriate amount of $H_2SO_4 $solution to the conical flask to provide an acidic environment.
- Load the $KMnO_4 $standard solution into an acid burette, zero and record the initial reading.
- Start the titration and shake while dripping. Note that the titration speed is slow first and then fast. When approaching the end point, slow down until the solution is reddish and does not fade within half a minute. Record the reading of the $KMnO_4 $solution at the end point of titration.
3. ** Parallel experiment **
- Repeat the above titration operation 2-3 times to record the data of each experiment.
5. Data recording and processing
1. ** Data Record **
| Number of Experiments | $H_2O_2 $Solution Volume (mL) | $KMnO_4 $Initial Solution Reading (mL) | $KMnO_4 $Solution Endpoint Reading (mL) | $KMnO_4 $Solution Consumption Volume (mL) |
| :---: | :---: | :---: | :---: | :---: |
| 1 | | | | |
| 2 | | | | |
| 3 | | | | |
2 . ** Data Processing **
- According to the chemical reaction equation, $n (H_2O_2) =\ frac {5} {2} n (KMnO_4) $.
- from $c =\ frac {n} {V} $ ($c $is the amount concentration of the substance, $n $is the amount of the substance, $V $is the volume of the solution) to obtain:
$c (H_2O_2) =\ frac {\ frac {5} {2} c (KMnO_4) V (KMnO_4) } {V (H_2O_2) } $
where $c (KMnO_4) $is the concentration of $KMnO_4 $standard solution, $V (KMnO_4) $is the volume of the solution consumed $KMnO_4 $, and $V (H_2O_2) $is the volume of the solution taken $H_2O_2 $.
- Calculate the concentration of $H_2O_2 $in each experiment, and calculate the average value, while calculating the relative deviation, to test the precision of the experimental results.
6. Precautions
1. At the beginning of titration, the addition speed of the $KMnO_4 $solution should be slow, because the reaction rate is slow at the beginning. After generating a certain amount of $Mn ^ {2 +} $, due to the catalytic action of $Mn ^ {2 +} $, the reaction rate will be accelerated. At this time, the titration speed can be appropriately accelerated, but it still needs to be shaken while dripping.
2. The judgment of the titration end point should be accurate. If the reddish color does not fade within half a minute, it is the end point. If the color fades too fast, it means that the end point has not been reached, and the titr 3. During the experiment, attention should be paid to keeping the instrument clean and dry to avoid the introduction of impurities affecting the experimental results.

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