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.
Which indicator is used in titration of COD test?
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 titration method is used to determine COD in water?
It consists of the amount of oxygen required for the organic matter to be oxidized by a chemical oxidant (usually potassium dichromate in acid medium). The sample is digested for 2 h at 150°C. COD is indirectly measured through Cr(VI) or Cr(III) contents by titration or UV–vis spectrophotometry.
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 reagent is used for measurement of COD?
The most general COD determination uses potassium dichromate (K2Cr2O7) in excess in an acidic medium with the aid of silver sulfate (Ag2SO4) as a catalyst, and mercuric sulfate (HgSO4) added to remove interference of chlorides.
How do you measure 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.
How do you test for BOD and COD in water?
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.
Which method is used for COD?
The traditional chemical oxygen demand (COD) analysis method is the wet chemistry method. This involves a two hour digestion at high heat under acidic conditions in which potassium dichromate acts as the oxidant for any organic material present in a water sample.
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.
Why do we use reflux method for determining COD?
It is used to indicate organic matter contamination and it helps in knowing overall organic load to the receiving body. There are two methods for COD determination. The first method: open reflux method is suitable for a wide range of wastes where large volume of sample is required (for samples with COD= 50 mg O2/L).
Which test is carried out when sufficient amount of water is available?
pH: pH test strips and color disk tests are widely available. More expensive, higher-tech options include electrode-based pH meters. pH is a measure of hydrogen ion activity, which means that it tells us how acidic or basic the water is.
Why do we need to determine COD?
COD is useful in terms of water quality by providing a metric to determine the effect an effluent will have on the receiving body, much like biochemical oxygen demand (BOD).
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.
How do you do a COD test in a lab?
Dissolve 9.8 g ferrous ammonium sulfate in a solution of 100 ml of distilled water and 20 ml concentrated Sulfuric acid. Cool the solution and make up the solution to 1000 ml of distilled water. Standardize the solution to determine the actual concentration to calculate the chemical oxygen demand.
What is COD & BOD in water?
The biochemical oxygen demand (BOD) represents the amount of dissolved oxygen (DO) consumed by biological organisms when they decompose organic matter in water. The chemical oxygen demand (COD) is the amount of oxygen consumed when the water sample is chemically oxidised.
What is COD and BOD used for?
Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) are two of the most important parameters to characterise (measure the degree of pollution) of wastewater. BOD, the biological demand for oxygen a source of water has, is the amount of oxygen used by microorganisms to break down organic substances.
What is COD how COD is measured in polluted water state the significance of COD?
The chemical oxygen demand (COD) is a measure of water and wastewater quality. The COD test is often used to monitor water treatment plant efficiency. This test is based on the fact that a strong oxidizing agent, under acidic conditions, can fully oxidize almost any organic compound to carbon dioxide.
How does a spectrophotometer measure COD?
The COD can be easily determined using a spectroscopy method based on the oxidation of the organic matter by potassium dichromate (K 2 Cr 2 O 7 ), which is converted to potassium chromate (K 2 CrO 4 ) in the presence of mercury sulfate (HgSO 4 ) and silver sulfate (AgSO 4 ).
Which are interfering with the determination of COD?
Abstract. Chemical oxidation demand (COD) is one of the most important determination indicators of landfill leachate. However, the presence of high concentration chloride in leachate generates interference, which hasn’t caused enough concern.
Which test is carried out when sufficient amount of water is not available Mcq?
The correct answer is Filtration.
What is used to find out the amount of residual chlorine in water?
There are three main methods to test free chlorine residual in drinking water in the field in developing countries: 1) Pool test kits, 2) Color-wheel test kits, and 3) Digital colorimeters.
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