Shanxian Chemical
SUPPLEMENTS
Hydrogen Peroxide Analysis Lab
Peroxide analysis experiment
1. Purpose of the experiment
The purpose of this experiment is to accurately determine the content of hydrogen peroxide ($H_2O_2 $) by a specific method, master the relevant chemical analysis skills and principles, and understand the application of redox reaction in quantitative analysis.
2. Experimental principle
Hydrogen peroxide is oxidizing and can redox with potassium iodide ($KI $) in an acidic medium to generate elemental iodine ($I_2 $). The reaction equation is: $H_2O_2 + 2KI + H_2SO_4 = I_2 + K_2SO_4 + 2H_2O $. The generated iodine can react with sodium thiosulfate ($Na_2S_2O_3 $). Using starch as an indicator, the content of hydrogen peroxide is calculated according to the volume of the standard solution of sodium thiosulfate consumed. The reaction equation is: $I_2 + 2Na_2S_2O_3 = 2NaI + Na_2S_4O_6 $.
III. Experimental instruments and reagents
1. ** Instruments **: acid burette, pipette, volumetric flask, conical bottle, iodine measuring bottle, washing bottle, analytical balance.
2. ** Reagent **: Hydrogen peroxide sample, potassium iodide solid, sulfuric acid solution ($1mol/L $), sodium thiosulfate standard solution ($0.1mol/L $), starch solution (0.5 dollars\% $).
IV. Experimental steps
1. ** Sample preparation **: Accurately remove a certain volume of hydrogen peroxide sample solution into an iodine flask.
2. ** The reaction proceeds **: Add an appropriate amount of potassium iodide solid to the iodine flask, and then add a certain volume of sulfuric acid solution. Quickly cap the bottle, seal it with water, and leave it in a dark place for a period of time to make the reaction fully proceed.
3. ** Titration operation **: Titrate the solution in the iodine flask with sodium thiosulfate standard solution. When the solution is light yellow, add a few drops of starch solution. Continue the titration until the blue color just disappears. Record the volume of the consumed sodium thiosulfate standard solution.
4. ** Parallel experiment **: Repeat the above steps 2 dollars - 3 $times to ensure the accuracy of the experimental data.
V. Record and processing of experimental data
1. ** Data Record **
| Number of Experiments | Hydrogen Peroxide Sample Volume ($mL $) | Consumption of Sodium Thiosulfate Standard Solution Volume ($mL $) |
| :---: | :---: | :---: |
| 1 | [Specific Value 1] |
| 2 | [Specific Value 2] | [Specific Value 2] |
| 3 | [Specific Value 3] | [Specific Value 3] |
2. ** Data Processing **
According to the chemical reaction equation, the quantity relationship of the substance can be obtained: $n (H_2O_2) =\ frac {1} {2} n (Na_2S_2O_3) $.
The concentration of hydrogen peroxide $c (H_2O_2) $is calculated as: $c (H_2O_2) =\ frac {c (Na_2S_2O_3) \ times V (Na_2S_2O_3) } {2\ times V (H_2O_2) } $, where $c (Na_2S_2O_3) $is the concentration of the sodium thiosulfate standard solution, $V (Na_2S_2O_3) $is the volume of the sodium thiosulfate standard solution consumed, and $V (H_2O_2) $is the volume of the hydrogen peroxide sample.
Calculate the concentration of hydrogen peroxide in each experiment and average it.
6. Precautions
1. After adding potassium iodide and sulfuric acid, the cork should be quickly capped and sealed to prevent iodine volatilization.
2. During the titration process, the titration speed should be well controlled. When the end point is near, the titration should be slowly titrated to avoid excessive titration.
3. The starch solution should be added near the end point. Early addition may lead to starch adsorption of iodine and affect the titration results.
7. Experimental results and discussion
1. ** Results **: The concentration of hydrogen peroxide samples was calculated by experiment as [specific results].
2. ** Discussion **: Analyze the possible sources of errors in the experimental process, such as titration endpoint judgment error, pipetting operation error, reaction time control, etc., which affect the experimental results. Think about how to improve the experimental operation to improve the accuracy of the experiment.
1. Purpose of the experiment
The purpose of this experiment is to accurately determine the content of hydrogen peroxide ($H_2O_2 $) by a specific method, master the relevant chemical analysis skills and principles, and understand the application of redox reaction in quantitative analysis.
2. Experimental principle
Hydrogen peroxide is oxidizing and can redox with potassium iodide ($KI $) in an acidic medium to generate elemental iodine ($I_2 $). The reaction equation is: $H_2O_2 + 2KI + H_2SO_4 = I_2 + K_2SO_4 + 2H_2O $. The generated iodine can react with sodium thiosulfate ($Na_2S_2O_3 $). Using starch as an indicator, the content of hydrogen peroxide is calculated according to the volume of the standard solution of sodium thiosulfate consumed. The reaction equation is: $I_2 + 2Na_2S_2O_3 = 2NaI + Na_2S_4O_6 $.
III. Experimental instruments and reagents
1. ** Instruments **: acid burette, pipette, volumetric flask, conical bottle, iodine measuring bottle, washing bottle, analytical balance.
2. ** Reagent **: Hydrogen peroxide sample, potassium iodide solid, sulfuric acid solution ($1mol/L $), sodium thiosulfate standard solution ($0.1mol/L $), starch solution (0.5 dollars\% $).
IV. Experimental steps
1. ** Sample preparation **: Accurately remove a certain volume of hydrogen peroxide sample solution into an iodine flask.
2. ** The reaction proceeds **: Add an appropriate amount of potassium iodide solid to the iodine flask, and then add a certain volume of sulfuric acid solution. Quickly cap the bottle, seal it with water, and leave it in a dark place for a period of time to make the reaction fully proceed.
3. ** Titration operation **: Titrate the solution in the iodine flask with sodium thiosulfate standard solution. When the solution is light yellow, add a few drops of starch solution. Continue the titration until the blue color just disappears. Record the volume of the consumed sodium thiosulfate standard solution.
4. ** Parallel experiment **: Repeat the above steps 2 dollars - 3 $times to ensure the accuracy of the experimental data.
V. Record and processing of experimental data
1. ** Data Record **
| Number of Experiments | Hydrogen Peroxide Sample Volume ($mL $) | Consumption of Sodium Thiosulfate Standard Solution Volume ($mL $) |
| :---: | :---: | :---: |
| 1 | [Specific Value 1] |
| 2 | [Specific Value 2] | [Specific Value 2] |
| 3 | [Specific Value 3] | [Specific Value 3] |
2. ** Data Processing **
According to the chemical reaction equation, the quantity relationship of the substance can be obtained: $n (H_2O_2) =\ frac {1} {2} n (Na_2S_2O_3) $.
The concentration of hydrogen peroxide $c (H_2O_2) $is calculated as: $c (H_2O_2) =\ frac {c (Na_2S_2O_3) \ times V (Na_2S_2O_3) } {2\ times V (H_2O_2) } $, where $c (Na_2S_2O_3) $is the concentration of the sodium thiosulfate standard solution, $V (Na_2S_2O_3) $is the volume of the sodium thiosulfate standard solution consumed, and $V (H_2O_2) $is the volume of the hydrogen peroxide sample.
Calculate the concentration of hydrogen peroxide in each experiment and average it.
6. Precautions
1. After adding potassium iodide and sulfuric acid, the cork should be quickly capped and sealed to prevent iodine volatilization.
2. During the titration process, the titration speed should be well controlled. When the end point is near, the titration should be slowly titrated to avoid excessive titration.
3. The starch solution should be added near the end point. Early addition may lead to starch adsorption of iodine and affect the titration results.
7. Experimental results and discussion
1. ** Results **: The concentration of hydrogen peroxide samples was calculated by experiment as [specific results].
2. ** Discussion **: Analyze the possible sources of errors in the experimental process, such as titration endpoint judgment error, pipetting operation error, reaction time control, etc., which affect the experimental results. Think about how to improve the experimental operation to improve the accuracy of the experiment.
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