Shanxian Chemical
SUPPLEMENTS
HydrogenPeroxideTitrationPotassiumPermanganate
Titration of peroxide and potassium permanganate
Objective
To investigate the redox titration reaction between hydrogen peroxide and potassium permanganate, and to determine the concentration of hydrogen peroxide solution through experimental operation.
Experimental principle
Hydrogen peroxide ($H_2O_2 $) and potassium permanganate ($KMnO_4 $) Redox reaction occurs under acidic conditions. Potassium permanganate is a strong oxidant, in which manganese is reduced from + 7 valence to + 2 valence, while oxygen in hydrogen peroxide is oxidized from -1 valence to 0 valence. The chemical reaction equation is as follows:
$2KMnO_4 + 5H_2O_2 + 3H_2SO_4 = K_2SO_4 + 2MnSO_4 + 8H_2O + 5O_2 ↑ $
In this reaction, the concentration of hydrogen peroxide can be calculated based on the amount of potassium permanganate solution and its stoichiometric relationship with hydrogen peroxide.
Experimental Instruments and Reagents
1. ** Instruments **: acid burette, conical bottle, pipette, volumetric bottle, measuring cylinder, glass rod, rubber head dropper, iron frame, burette clip.
2. ** Reagents **: known concentrations of potassium permanganate standard solution, hydrogen peroxide solution to be tested, dilute sulfuric acid solution ($3mol/L $).
Experimental steps
1. ** Preparation **
- ** Check the instrument **: Carefully check whether the acid burette is leaking. If there is any leakage, it needs to be treated or replaced.
- ** Rinse the burette **: Rinse the acid burette 2-3 times with a small amount of potassium permanganate standard solution to be installed. Each time, the rinse liquid is discharged from the tip of the burette to ensure that the solution attached to the inner wall of the burette is consistent with the solution to be installed to avoid concentration changes.
- ** Liquid filling **: Carefully pour the potassium permanganate standard solution into an acid burette so that the liquid level is 2-3cm above the "0" scale line, remove bubbles at the tip of the burette, adjust the liquid level to "0" scale or below the "0" scale, and record the initial reading of $V_1 $.
2. ** Measure the liquid to be tested **
- Take a certain volume (e.g. 25.00mL) of the hydrogen peroxide solution to be tested with a pipette and place it in a clean conical bottle.
- Add an appropriate amount of dilute sulfuric acid solution (about 10mL) to the conical bottle to provide an acidic reaction environment.
3. ** Titration Operation **
- Place the conical flask under the acid burette and start the titration. Control the piston of the burette with your left hand, hold the bottleneck of the conical flask with your right hand, and gently shake the conical flask while dripping to fully mix the solution.
- During the titration process, it is necessary to closely observe the change of the color of the solution in the conical flask. At the beginning, the color of the solution changes slowly, and as the titration proceeds, the reaction rate accelerates. When the solution changes from colorless to reddish and does not fade within half a minute, it is the end point of the titration. Record the reading of the burette at this time $V_2 $.
4. ** Repeat the experiment **
To reduce the experimental error, repeat the above experimental operation 2-3 times, and record the amount of potassium permanganate standard solution in
Data recording and processing
1. ** Data recording **
| Number of experiments | Initial reading of potassium permanganate standard solution $V_1/mL $| Endpoint reading of potassium permanganate standard solution $V_2/mL $| Potassium permanganate standard solution volume $V = V_2 - V_1/mL $|
|---|---|---|---|
| 1 | | | |
| 2 | | | |
| 3 | | | |
2. ** Data Processing **
According to the chemical reaction equation, $n (H_2O_2) =\ frac {5} {2} n (KMnO_4) $.
Let the concentration of potassium permanganate standard solution be $c (KMnO_4) $, according to $c (H_2O_2) =\ frac {\ frac {5} {2} c (KMnO_4) V (KMnO_4) } {V (H_2O_2) } $, calculate the concentration of hydrogen peroxide solution in each experiment $c (H_2O_2) $, and find the average value.
Precautions
1. Potassium permanganate solution has strong oxidation and will corrode rubber tubes, so acid burettes are required.
2. During the titration process, the color change of the solution is more obvious. Pay attention to control the titration speed. When approaching the end point, it should be added dropwise to avoid dripping over the end point.
3. After the experiment is completed, the experimental instrument should be cleaned in time, especially the acid burette. Rinse it with distilled water and dry it upside down to prevent the residual solution from corroding the instrument.
Objective
To investigate the redox titration reaction between hydrogen peroxide and potassium permanganate, and to determine the concentration of hydrogen peroxide solution through experimental operation.
Experimental principle
Hydrogen peroxide ($H_2O_2 $) and potassium permanganate ($KMnO_4 $) Redox reaction occurs under acidic conditions. Potassium permanganate is a strong oxidant, in which manganese is reduced from + 7 valence to + 2 valence, while oxygen in hydrogen peroxide is oxidized from -1 valence to 0 valence. The chemical reaction equation is as follows:
$2KMnO_4 + 5H_2O_2 + 3H_2SO_4 = K_2SO_4 + 2MnSO_4 + 8H_2O + 5O_2 ↑ $
In this reaction, the concentration of hydrogen peroxide can be calculated based on the amount of potassium permanganate solution and its stoichiometric relationship with hydrogen peroxide.
Experimental Instruments and Reagents
1. ** Instruments **: acid burette, conical bottle, pipette, volumetric bottle, measuring cylinder, glass rod, rubber head dropper, iron frame, burette clip.
2. ** Reagents **: known concentrations of potassium permanganate standard solution, hydrogen peroxide solution to be tested, dilute sulfuric acid solution ($3mol/L $).
Experimental steps
1. ** Preparation **
- ** Check the instrument **: Carefully check whether the acid burette is leaking. If there is any leakage, it needs to be treated or replaced.
- ** Rinse the burette **: Rinse the acid burette 2-3 times with a small amount of potassium permanganate standard solution to be installed. Each time, the rinse liquid is discharged from the tip of the burette to ensure that the solution attached to the inner wall of the burette is consistent with the solution to be installed to avoid concentration changes.
- ** Liquid filling **: Carefully pour the potassium permanganate standard solution into an acid burette so that the liquid level is 2-3cm above the "0" scale line, remove bubbles at the tip of the burette, adjust the liquid level to "0" scale or below the "0" scale, and record the initial reading of $V_1 $.
2. ** Measure the liquid to be tested **
- Take a certain volume (e.g. 25.00mL) of the hydrogen peroxide solution to be tested with a pipette and place it in a clean conical bottle.
- Add an appropriate amount of dilute sulfuric acid solution (about 10mL) to the conical bottle to provide an acidic reaction environment.
3. ** Titration Operation **
- Place the conical flask under the acid burette and start the titration. Control the piston of the burette with your left hand, hold the bottleneck of the conical flask with your right hand, and gently shake the conical flask while dripping to fully mix the solution.
- During the titration process, it is necessary to closely observe the change of the color of the solution in the conical flask. At the beginning, the color of the solution changes slowly, and as the titration proceeds, the reaction rate accelerates. When the solution changes from colorless to reddish and does not fade within half a minute, it is the end point of the titration. Record the reading of the burette at this time $V_2 $.
4. ** Repeat the experiment **
To reduce the experimental error, repeat the above experimental operation 2-3 times, and record the amount of potassium permanganate standard solution in
Data recording and processing
1. ** Data recording **
| Number of experiments | Initial reading of potassium permanganate standard solution $V_1/mL $| Endpoint reading of potassium permanganate standard solution $V_2/mL $| Potassium permanganate standard solution volume $V = V_2 - V_1/mL $|
|---|---|---|---|
| 1 | | | |
| 2 | | | |
| 3 | | | |
2. ** Data Processing **
According to the chemical reaction equation, $n (H_2O_2) =\ frac {5} {2} n (KMnO_4) $.
Let the concentration of potassium permanganate standard solution be $c (KMnO_4) $, according to $c (H_2O_2) =\ frac {\ frac {5} {2} c (KMnO_4) V (KMnO_4) } {V (H_2O_2) } $, calculate the concentration of hydrogen peroxide solution in each experiment $c (H_2O_2) $, and find the average value.
Precautions
1. Potassium permanganate solution has strong oxidation and will corrode rubber tubes, so acid burettes are required.
2. During the titration process, the color change of the solution is more obvious. Pay attention to control the titration speed. When approaching the end point, it should be added dropwise to avoid dripping over the end point.
3. After the experiment is completed, the experimental instrument should be cleaned in time, especially the acid burette. Rinse it with distilled water and dry it upside down to prevent the residual solution from corroding the instrument.
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