How is Winkler method calculated?
Table of Contents
How is Winkler method calculated?
Winkler Method Calculation
- Answer:
- Step 1: Determine the average volume of delivered.
- Step 2: Determine the number of moles of sodium thiosulfate reacted.
- Step 3: Determine the moles of oxygen reacted.
- Step 4: Calculate the concentration of the dissolved oxygen.
Which type of titration is Winkler’s method?
manual titration method
The Winkler method is a manual titration method for the determination of dissolved oxygen in a water sample. The analysis is often performed in the field to avoid delays that may result in a change in the oxygen content of the water.
Why Sulphuric acid is used in Winkler method?
Added sulfuric acid acidifies the solution and dissolves the precipitate. This new compound oxidizes the iodide from the alkaline iodine-azide reagent to iodine. Next, a starch indicator is added that will turn blue in the presence of iodine.
Why mnso4 is used in Winkler method?
Manganese sulfate and potassium hydroxide are added to the sample, forming manganese hydroxide. This reduces the dissolved oxygen, forming a brown precipitate. Alkaline iodide-azide reagent is added to correct for the presence of nitrates found in wastewater samples that can interfere with the oxidation procedure.
How do you calculate ppm of dissolved oxygen in water?
1 Determine water temperature in degrees C and find the value on the temperature scale. F to C conversion: [(F – 32) x 5] ÷ 9 2 Determine dissolved oxygen (DO) and find the value on the lower scale (Note: you result can be in mg/L or ppm).
Why mnso4 is added in Winkler’s method?
Why do we need to add starch as indicator in the Winkler method?
Why starch is added at the end of titration in Winkler method? The Starch-Iodide complex is not very soluble in water, so the starch is added near the endpoint of an Iodine titration, when the Iodine concentration is low.
Why is starch used in Winkler method?
The starch “indicator” (which forms a distinctly colored complex with the free iodine) is used to provide an unmistakable visual endpoint for the titration. The concentration of dissolved oxygen (DO) is one of the most important indicators of the overall health of a body of water.
Why starch is added in Winkler method?
The Starch-Iodide complex is not very soluble in water, so the starch is added near the endpoint of an Iodine titration, when the Iodine concentration is low. This eliminates errors due to the fact that some Iodine may remain adsorbed on the complex and go undetected.
What is the formula for dissolved oxygen?
Definition. Dissolved oxygen (DO) is the amount of elemental oxygen (chemical symbol O2, molecular wt 31.99 g/mol) dissolved in fresh or salt waters.
Why is azide used in Winkler method?
In the analysis, manganous ion reacts with the dissolved oxygen present in the alkaline solution to form a manganese (IV) oxide hydroxide flocculent. Azide is added at this time to suppress interference from any nitrite present which would react with the iodide.
Why is sulfuric acid added in Winkler method?
4. Add 6–7 drops of concentrated sulfuric acid to each sample tube, stopper and invert several times to mix (the instructor may wish to perform this step). The acid solubilizes the precipitate, giving a clear, yellow-gold solution.
What is the purpose of adding MnSO4 in Winkler’s method?
In the Winkler method,add MnSO4 and basic KI solution to the water sample. The product,Mn(OH)2 is oxided by the dissolved oxygen to Mn(OH)3, which reacts with KI when add H2SO4 to make the solution acid. The produced I2 is titrated by Na2S2O3 solution. The dissolved oxygen can be valued.
Which of the following indicator is used in Winkler’s method?
The Winkler Method is a technique used to measure dissolved oxygen in freshwater systems. Dissolved oxygen is used as an indicator of the health of a water body, Where higher dissolved oxygen concentrations are correlated with high productivity and little pollution.
