indicator ferroin.
Detailed Solution The excess potassium dichromate is titrated with ferrous ammonium sulphate (FAS) until all of the excess oxidizing agent has been reduced to Cr3+. The oxidation-reduction indicator ferroin is also added during this titration as it changes its color from red to pale blue when oxidized.
Which indicator is used when the titration is carried out to determine the amount of COD present in a water sample?
Ferroin
Which of these is the used as the indicator when the titration is carried out to determine the amount of COD present in a sample. Explanation: Ferroin is the indicator used while titration is carried out to determine the COD present in a water sample. The sample is titrated against ferrous ammonium sulphate.
Why FAS is used in COD?
In the titration method for determining COD, the excess dichromate is reacted with a reducing agent, ferrous ammonium sulfate. As the ferrous ammonium sulfate (FAS) is added slowly, the excess dichromate is converted into its trivalent form. As soon as all the excess dichromate reacts, an equivalence point is reached.
How do you determine COD in water samples?
The COD test uses a chemical (potassium dichromate in a 50% sulfuric acid solution) that “oxidizes” both organic (predominate) and inorganic substances in a wastewater sample, which results in a higher COD concentration than BOD concentration for the same wastewater sample since only organic compounds are consumed
Which indicator is used in determination of COD?
Using potassium dichromate
Most commonly, a 0.25 N solution of potassium dichromate is used for COD determination, although for samples with COD below 50 mg/L, a lower concentration of potassium dichromate is preferred.
Which chemical is used as an indicator for COD titration?
ferroin
2.1 Organic and oxidizable inorganic substances in an aqueous sample are oxidized by potassium dichromate solution in 50 percent (by volume) sulfuric acid solution. The excess dichromate is titrated with standard ferrous ammonium sulfate using orthophenanthroline ferrous complex (ferroin) as an indicator.
How do you make COD FAS solution?
The ferrous ammonium sulfate (FAS) titrant must be standardized daily by the following procedure: Dilute 10ml of standard potassium dichromate (K2Cr2O7) solution to 100ml with distilled water. Slowly add 30ml of concentrated sulphuric acid and cool to room temperature.
What are the methods of measuring COD?
COD is measured via a laboratory assay in which a sample is incubated with a strong chemical oxidant for a specified time interval and at constant temperature (usually 2 h at 150°C). The most commonly used oxidant is potassium dichromate, which is used in combination with boiling sulphuric acid.
What is COD and How Is It measured?
COD is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution, which in SI units is milligrams per liter (mg/L). A COD test can be used to easily quantify the amount of organics in water.
How do you determine COD and BOD?
Testing for BOD involves incubating a sealed water sample at 20C for five days, followed by measuring the difference in oxygen content before and after incubation. COD measures how much DO is consumed by the oxidation of organic matter and inorganic compounds such as ammonia or nitrite under controlled conditions.
Why Ag2SO4 is used in COD?
The COD analysis uses silver sulfate (Ag2SO4) as a catalyst, mercury sulfate (Hg2SO4) to eliminate chloride interference, ferric ammonium sulfate ((NH4)2. Fe(SO4).
Which catalyst is used in COD experiment?
Abstract. In this study, 10% CuO/Al2O3 catalyst was used in a catalytic wet-air oxidation process to remove chemical oxygen demand (COD) and color from experimentally designed wastewater containing lignin.
When the titration ends in a COD test the color of the solution being titrated is?
The oxidation-reduction indicator ferroin is also added during this titration as it changes its color from red to pale blue when oxidized. Important point: COD test is also called dichromate-oxygen demand test.
Which Colour is obtained at the end point in titration between FAS and k2cr2o7?
This reading and all other buret readings should be estimated to the nearest 0.01 mL. 4. Titrate the iron solution in the flask. The intense purple color produced by the first drop of excess K2Cr2O7 signals the end point for the titration.
How do you find molarity from FAS?
Molarity of FAS solution=(Volume 0.0167M [math]displaystyle{ K_2Cr_2O_7 }[/math] solution titrated, mL)/(Volume FAS used in titration, mL) × 0.1.
What is COD Mcq?
Quality and Characteristics of Sewage MCQ Question 4
(i) The COD (Chemical oxygen demand) test is used to measure the content of organic matter of waste water, both biodegradable and non-biodegradble.
What is COD how COD is measured in polluted water state the significance of COD?
Chemical oxygen demand (COD) is the amount of dissolved oxygen that must be present in water to oxidize chemical organic materials, like petroleum. COD is used to gauge the short-term impact wastewater effluents will have on the oxygen levels of receiving waters.
Why is it important to determine COD in wastewater treatment?
In wastewater treatment, the Chemical Oxygen Demand (COD) is an important measurement for the amount of oxygen that is required to break down pollutants (organic substances) in water. The chemical oxygen demand can be measured using different methods, direct or indirect.
Does BOD COD water analysis?
BOD analysis is similar in function to chemical oxygen demand (COD) analysis, in that both measure the amount of organic compounds in water. However, COD analysis is less specific, since it measures everything that can be chemically oxidized, rather than just levels of biologically oxidized organic matter.
What is the normality of FAS solution?
Ferrous Ammonium Sulfate, 0.1 Normal, Actual Normality = 0.0995 – 0.1005, Aqueous Solution.
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