Video 3

Senia Asabila
9 Mar 202506:45

Summary

TLDRThis chemistry experiment demonstrates the process of COD (Chemical Oxygen Demand) analysis. It involves using a detergent wastewater sample and several reagents such as sulfuric acid, iron ammonium sulfate, and a digestion solution. The procedure includes mixing the sample with reagents, heating the solution, and performing a titration. During the experiment, changes in color indicate reactions, such as the transformation of Cr2O7^2- ions to Cr3+ ions, which helps determine the concentration of the contaminant. The final stage involves titrating the sample with a ferrous sulfate solution and observing a color change to identify the COD value.

Takeaways

  • 😀 The experiment being conducted is titled 'COD Analysis' and is part of a Chemistry Analytical Lab.
  • 😀 The materials needed for the experiment include wastewater sample (detergent waste), 0.05 Molar FAS (Ferrous Ammonium Sulfate), digestion solution, sulfuric acid reagent, and ferroin indicator.
  • 😀 The necessary equipment includes a glass beaker, culture tube, pipettes, burette, stative, clamp, oil bath, and electric heater.
  • 😀 The first step involves mixing the wastewater sample, digestion solution, and sulfuric acid reagent.
  • 😀 2.5 mL of wastewater sample (detergent waste) is taken, followed by adding 1.5 mL of digestion solution and 3.5 mL of sulfuric acid reagent.
  • 😀 During this step, a phenomenon occurs where the solution volume rises due to the chemical reaction.
  • 😀 The mixture is then placed in a culture tube and heated in an oil bath at 150°C for 2 hours.
  • 😀 A blank solution is also prepared by replacing the wastewater sample with aquades, which is then also heated.
  • 😀 The color change observed during the reaction indicates the completion of the process. A yellow sample indicates the presence of Cr2O7²-, and a green color shows that Cr2O7²- has reacted completely into Cr3+.
  • 😀 If the wastewater sample turns green after heating, it means the concentration of the sample is too high and the Cr2O7²- ion has been fully reduced.
  • 😀 After heating, titration is performed by adding FAS solution and ferroin indicator, which results in a color change from yellow-green to reddish-brown.
  • 😀 The final step involves noting the titration volume used in the experiment.

Q & A

  • What is the title of the experiment conducted in the script?

    -The title of the experiment is 'COD Analysis'.

  • What sample is used for the COD analysis in the experiment?

    -The sample used in the experiment is wastewater, specifically detergent wastewater.

  • What chemicals are needed for the experiment?

    -The chemicals required are a 0.05 Molar FAS (ferroammonium sulfate) solution, digestion solution, sulfuric acid, and Ferroing indicator.

  • What equipment is necessary for the experiment?

    -The necessary equipment includes a glass beaker, test tubes, pipettes, volumetric pipette, clamps, oil bath, and electric heater.

  • How is the initial mixture prepared in the experiment?

    -The initial mixture is prepared by combining 2.5 mL of detergent wastewater sample, 1.5 mL of digestion solution, and 3.5 mL of sulfuric acid.

  • What happens to the solution after adding sulfuric acid?

    -The solution experiences a noticeable phenomenon where the solution color changes and rises.

  • What is the procedure for preparing the blank solution?

    -The blank solution is prepared similarly to the wastewater mixture, but the detergent wastewater is replaced with aquadest (distilled water).

  • At what temperature and for how long is the mixture heated?

    -The mixture is heated in an oil bath at 150°C for about 2 hours.

  • What is the significance of the color change in the sample during heating?

    -A yellow sample that remains yellow after heating indicates the presence of Cr2O7^2- ions in the solution, while a sample that turns green shows that all Cr2O7^2- ions have reacted to form Cr^3+ ions.

  • What is the purpose of the titration in the experiment?

    -The titration is performed to determine the volume of the titrant used, with the color change indicating the endpoint of the reaction.

  • What color change occurs during the titration?

    -During the titration, the solution changes from a yellow-green color to a reddish-brown color.

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Related Tags
COD AnalysisChemical ExperimentWastewater TreatmentDetergent WasteLaboratory ProcedureTitrationAnalytical ChemistryScience EducationWater PollutionLab Safety