Shanxian Chemical
SUPPLEMENTS
Redox Titration Hydrogen Peroxide
Redox Titration Hydrogen Peroxide
1. Experimental Purpose
Master the principle and method of redox titration for the determination of hydrogen peroxide content, and be skilled in using burettes and other instruments for quantitative analysis operations.
2. Experimental Principle
Hydrogen peroxide ($H_2O_2 $) is oxidizing and reducing, and can be oxidized by $KMnO_4 $in acidic media. The reaction equation is:
$2KMnO_4 + 5H_2O_2 + 3H_2SO_4 = K_2SO_4 + 2MnSO_4 + 5O_2 ↑ + 8H_2O $
This reaction is its own indicator. Titration until the solution is reddish and does not fade within half a minute is the end point. According to the concentration of $KMnO_4 $standard solution and the volume consumed by titration, the content of $H_2O_2 $can be calculated.
III. Experimental instruments and reagents
1. ** Instruments **: acid burette, conical bottle, pipette, volumetric bottle, measuring cylinder, etc.
2. ** Reagents **: $KMnO_4 $standard solution (known exact concentration), $H_2SO_4 $solution (3 mol/L), hydrogen peroxide sample.
IV. Experimental steps
1. ** Dilution of hydrogen peroxide sample **
Accurately pipette a volume ($V_1 $mL) of hydrogen peroxide sample with a pipette, place in a 250 dollars $mL volumetric flask, dilute to scale with water, and shake well.
2. ** Titration **
Pipette 25 dollars $mL of diluted hydrogen peroxide solution from a volumetric flask, place in a conical flask, add 10 dollars $mL 3 dollars $mol/L of $H_2SO_4 $solution. Load an acid burette with a $KMnO_4 $standard solution and record the initial reading of $V_ {start} $.
Then use $KMnO_4 $standard solution to titrate the hydrogen peroxide solution. The titration speed should be slow at the beginning. After $Mn ^ {2 +} $is produced in the solution, the titration speed can be appropriately accelerated, but it still needs to be added dropwise, shaking while dripping, until the solution appears reddish and does not fade within half a minute, which is the end point. Record the reading of $KMnO_4 $standard solution at the end point of titration. $V_ {final} $.
3. ** Parallel experiment **
Repeat the above operation, perform 2 dollars - 3 $parallel experiments, calculate the content of hydrogen peroxide in each experiment, and calculate the average value.
5. Data recording and processing
1. ** DATA RECORD **
| Number of experiments | $KMnO_4 $Standard solution concentration (mol/L) | Pumped hydrogen peroxide sample volume (mL) | Pre-titration reading (mL) | Post-titration reading (mL) | Consumption $KMnO_4 $Standard solution volume (mL) |
| :---: | :---: | :---: | :---: | :---: | :---: |
| 1 | [Specific concentration value] | $V_1 $| $V_ {start 1} $| $V_ {End 1} $| $V_ {1} = V_ {End 1} - V_ {End 1} $|
| 2 | [Specific Concentration Value] | $V_1 $| $V_ {Start 2} $| $V_ {End 2} $| $V_ {2} = V_ {End 2} - V_ {Start 2} $|
| 3 | [Specific Concentration Value] | $V_1 $| $V_ {Start 3} $| $V_ {End 3} $| $V_ {3} = V_ {End 3} - V_ { Start 3} $|
2. ** Calculation of hydrogen peroxide content **
According to the reaction equation, $n (H_2O_2) =\ frac {5} {2} n (KMnO_4) $, then the hydrogen peroxide content $w (H_2O_2) $ (g/L) is calculated as:
$w (H_2O_2) =\ frac {\ frac {5} {2} c (KMnO_4) \ times V (KMnO_4) \ times M (H_2O_2) } {V_0}\ times1000 $
Where $c (KMnO_4) $is the concentration (mol/L) of $KMnO_4 $standard solution, $V (KMnO_4) $is the titration consumption $KMnO_4 $standard solution volume (L), $M (H_2O_2) $is the molar mass of hydrogen peroxide (34.01) G/mol), $V_0 $is the volume (L) of the absorbed hydrogen peroxide sample diluted for titration, where $V_0 = 0.025 $L.
Calculate the hydrogen peroxide content of each experiment separately, and calculate the average value, and calculate the relative deviation at the same time.
6. Precautions
1. $KMnO_4 $The solution is easy to decompose in light and should be stored in a brown bottle.
2. The speed at the beginning of titration should not be too fast, otherwise the added $KMnO_4 $solution will not react with $H_2O_2 $in time, and will decompose in a hot acidic solution, resulting in high results.
3. The reddish color at the end point of titration will gradually fade after being placed in the air. This is due to the slow reaction of reducing substances in the air with $MnO_4 ^ - $. If it does not fade within half a minute, it is the end point.
1. Experimental Purpose
Master the principle and method of redox titration for the determination of hydrogen peroxide content, and be skilled in using burettes and other instruments for quantitative analysis operations.
2. Experimental Principle
Hydrogen peroxide ($H_2O_2 $) is oxidizing and reducing, and can be oxidized by $KMnO_4 $in acidic media. The reaction equation is:
$2KMnO_4 + 5H_2O_2 + 3H_2SO_4 = K_2SO_4 + 2MnSO_4 + 5O_2 ↑ + 8H_2O $
This reaction is its own indicator. Titration until the solution is reddish and does not fade within half a minute is the end point. According to the concentration of $KMnO_4 $standard solution and the volume consumed by titration, the content of $H_2O_2 $can be calculated.
III. Experimental instruments and reagents
1. ** Instruments **: acid burette, conical bottle, pipette, volumetric bottle, measuring cylinder, etc.
2. ** Reagents **: $KMnO_4 $standard solution (known exact concentration), $H_2SO_4 $solution (3 mol/L), hydrogen peroxide sample.
IV. Experimental steps
1. ** Dilution of hydrogen peroxide sample **
Accurately pipette a volume ($V_1 $mL) of hydrogen peroxide sample with a pipette, place in a 250 dollars $mL volumetric flask, dilute to scale with water, and shake well.
2. ** Titration **
Pipette 25 dollars $mL of diluted hydrogen peroxide solution from a volumetric flask, place in a conical flask, add 10 dollars $mL 3 dollars $mol/L of $H_2SO_4 $solution. Load an acid burette with a $KMnO_4 $standard solution and record the initial reading of $V_ {start} $.
Then use $KMnO_4 $standard solution to titrate the hydrogen peroxide solution. The titration speed should be slow at the beginning. After $Mn ^ {2 +} $is produced in the solution, the titration speed can be appropriately accelerated, but it still needs to be added dropwise, shaking while dripping, until the solution appears reddish and does not fade within half a minute, which is the end point. Record the reading of $KMnO_4 $standard solution at the end point of titration. $V_ {final} $.
3. ** Parallel experiment **
Repeat the above operation, perform 2 dollars - 3 $parallel experiments, calculate the content of hydrogen peroxide in each experiment, and calculate the average value.
5. Data recording and processing
1. ** DATA RECORD **
| Number of experiments | $KMnO_4 $Standard solution concentration (mol/L) | Pumped hydrogen peroxide sample volume (mL) | Pre-titration reading (mL) | Post-titration reading (mL) | Consumption $KMnO_4 $Standard solution volume (mL) |
| :---: | :---: | :---: | :---: | :---: | :---: |
| 1 | [Specific concentration value] | $V_1 $| $V_ {start 1} $| $V_ {End 1} $| $V_ {1} = V_ {End 1} - V_ {End 1} $|
| 2 | [Specific Concentration Value] | $V_1 $| $V_ {Start 2} $| $V_ {End 2} $| $V_ {2} = V_ {End 2} - V_ {Start 2} $|
| 3 | [Specific Concentration Value] | $V_1 $| $V_ {Start 3} $| $V_ {End 3} $| $V_ {3} = V_ {End 3} - V_ { Start 3} $|
2. ** Calculation of hydrogen peroxide content **
According to the reaction equation, $n (H_2O_2) =\ frac {5} {2} n (KMnO_4) $, then the hydrogen peroxide content $w (H_2O_2) $ (g/L) is calculated as:
$w (H_2O_2) =\ frac {\ frac {5} {2} c (KMnO_4) \ times V (KMnO_4) \ times M (H_2O_2) } {V_0}\ times1000 $
Where $c (KMnO_4) $is the concentration (mol/L) of $KMnO_4 $standard solution, $V (KMnO_4) $is the titration consumption $KMnO_4 $standard solution volume (L), $M (H_2O_2) $is the molar mass of hydrogen peroxide (34.01) G/mol), $V_0 $is the volume (L) of the absorbed hydrogen peroxide sample diluted for titration, where $V_0 = 0.025 $L.
Calculate the hydrogen peroxide content of each experiment separately, and calculate the average value, and calculate the relative deviation at the same time.
6. Precautions
1. $KMnO_4 $The solution is easy to decompose in light and should be stored in a brown bottle.
2. The speed at the beginning of titration should not be too fast, otherwise the added $KMnO_4 $solution will not react with $H_2O_2 $in time, and will decompose in a hot acidic solution, resulting in high results.
3. The reddish color at the end point of titration will gradually fade after being placed in the air. This is due to the slow reaction of reducing substances in the air with $MnO_4 ^ - $. If it does not fade within half a minute, it is the end point.
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