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AS silver ions first react with Cloride ions in the sample(equivalence point) and when all the chloride ions are consumed we have to add more silver nitrate solution to increase its concentration to a level where it can precipitate chromate ions as silver chromate precipites (reddish brown ppts) this is the end point . so remove this error of equivalence point detection we take the same volume of indicator (chromate solution) in a flask labelled blank and add water into this flask (the same volume as that of sample solution) and then titrate this blank labelled flask with standard silver nitrate solution and note the volume of titrant consumed (blank volume),then calculations for real equivalence point can be made as:
equivalence point=(end point)-(blank volume)
Blank titration is necessary in the Mohr method to account for any impurities present in the reagents or in the sample. It helps to ensure that the color change observed during the titration is solely due to the analyte of interest being titrated, and not influenced by impurities that could interfere with the accuracy of the results.
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Why is not possible to determine iodide by mohr titration?
Iodide cannot be determined by Mohr titration because it does not form a precipitate with silver nitrate. Mohr titration relies on the formation of a colored precipitate to indicate the end point, which is not observed in the case of iodide ions. Other methods, such as iodometric titration or spectrophotometry, are used to determine iodide ions quantitatively.
Why in Mohrs method of titration pH is maintain as neutral?
In Mohr's method of titration, the pH is maintained as neutral in order to ensure that the indicator used in the titration changes color sharply at the equivalence point. This helps in accurately determining the end point of the titration, as the color change will be clearly visible when the reaction is complete. Maintaining a neutral pH also prevents any interference from acidic or basic impurities that could affect the accuracy of the titration.
What is the use of ferroin indicator in redox titration of Mohr's salt?
Ferroin indicator is used in the redox titration of Mohr's salt as it changes color when the Fe2+ ions are completely oxidized to Fe3+ ions. This color change helps in determining the end point of the titration, where all the Mohr's salt has been oxidized and no more Fe2+ ions are present.
Why HCl is used in titration of mohr salt and potassium dichromate?
Hydrochloric acid (HCl) is used in the titration of Mohr's salt and potassium dichromate because it reacts with Mohr's salt to form ferric chloride and with potassium dichromate to form chromium chloride. These reactions result in the formation of a color change in the solution which allows for the end point of the titration to be easily detected.
Why Mohr salt is called Mohr?
Mohr salt is named after the German chemist Karl Friedrich Mohr, who first synthesized it in 1855. He discovered the compound's chemical composition and properties that are frequently used in analytical chemistry and titration methods.
Why indicator blank is used in mohr method?
An indicator blank is used in the Mohr method to account for any color changes that may occur due to impurities in the indicator itself. By measuring the blank, you can subtract this error from the titration result, ensuring accurate determination of the analyte concentration.
Why we add conc sulphuric acid in mohr salt in the titration of mohr salt against potassium dichromate?
For preparation of standard solution of Mohr salt {FeSO4.(NH4)2SO4.6H2O}, it's necessary to add dilute H2SO4 to prevent the Fe2+ ions of Mohr salt solution from undergoing oxidation (to Fe3+).
Why is not possible to determine iodide by mohr titration?
Iodide cannot be determined by Mohr titration because it does not form a precipitate with silver nitrate. Mohr titration relies on the formation of a colored precipitate to indicate the end point, which is not observed in the case of iodide ions. Other methods, such as iodometric titration or spectrophotometry, are used to determine iodide ions quantitatively.
What is the difference between volhard and mohr methods?
The Volhard method is a titration method used to determine the concentration of halide ions in a solution using silver nitrate and potassium chromate as indicators. The Mohr method, on the other hand, is also a titration method used to determine the chloride ions concentration in a solution using silver nitrate and potassium chromate indicators. The key difference lies in the end point detection: Volhard method involves the use of a ferric alum indicator that forms a red-brown precipitate, while the Mohr method involves the formation of a red-brown silver chromate precipitate.
Why in Mohrs method of titration pH is maintain as neutral?
In Mohr's method of titration, the pH is maintained as neutral in order to ensure that the indicator used in the titration changes color sharply at the equivalence point. This helps in accurately determining the end point of the titration, as the color change will be clearly visible when the reaction is complete. Maintaining a neutral pH also prevents any interference from acidic or basic impurities that could affect the accuracy of the titration.
What is the use of ferroin indicator in redox titration of Mohr's salt?
Ferroin indicator is used in the redox titration of Mohr's salt as it changes color when the Fe2+ ions are completely oxidized to Fe3+ ions. This color change helps in determining the end point of the titration, where all the Mohr's salt has been oxidized and no more Fe2+ ions are present.
Why HCl is used in titration of mohr salt and potassium dichromate?
Hydrochloric acid (HCl) is used in the titration of Mohr's salt and potassium dichromate because it reacts with Mohr's salt to form ferric chloride and with potassium dichromate to form chromium chloride. These reactions result in the formation of a color change in the solution which allows for the end point of the titration to be easily detected.
What is the equivalent weight of mohr's salt in the titration of pottasium permanganate and mohr's salt?
The equivalent weight of Mohr's salt (ammonium iron(II) sulfate) is the molecular weight divided by the total positive charge of the cation(s) that are being titrated. In the titration of potassium permanganate with Mohr's salt, the equivalent weight of Mohr's salt is 88 g/mol (molecular weight) divided by the total positive charge of the cation(s) (in this case, 2), which equals 44 g/equivalent.
What are the limits for determination of chloride by the Mohr method?
The Mohr method for determining chloride ions has a detection limit of around 10-20 ppm and a quantitative limit of around 30-40 ppm. These limits can vary depending on the specific conditions and equipment used in the analysis.
Why Mohr salt is called Mohr?
Mohr salt is named after the German chemist Karl Friedrich Mohr, who first synthesized it in 1855. He discovered the compound's chemical composition and properties that are frequently used in analytical chemistry and titration methods.
Why mohr method is better than volhard method?
The Mohr method is typically preferred over the Volhard method for chloride titrations because it does not require a silver nitrate standard solution, making it more cost-effective and simpler to execute. Additionally, the Mohr method is more precise as it allows for a direct endpoint determination based on the formation of a specific silver chloride precipitate.
What are the uses of Mohr's salt?
Mohr's salt is primarily used as a reducing agent in various chemical reactions, such as in the laboratory synthesis of ammonia. It is also used in analytical chemistry for titration purposes, particularly in the determination of chloride ions. Additionally, Mohr's salt is employed in the production of pigments and dyes.
