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Potassium chromate is used as an indicator in argentometric titrations because it forms a red precipitate (silver chromate) in the presence of excess silver ions. This color change signals the end point of the titration, where all the chloride ions have reacted with silver ions. This makes it easy to visually detect when the reaction is complete.
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What is Fajan's method of argentometric titration?
Fajan's method of argentometric titration involves the use of potassium chromate as an indicator to detect the end point of a titration between silver ions and chloride ions. The indicator changes color from yellow to red when all the chloride ions have reacted with the silver ions, marking the end point of the titration.
Why mohr titration must be perform at a pH of neutral?
The reaction has to be carried out at neutral conditions because in acid the chromate indicator concentration decreases due to the reaction with the H+ ions, forming HCrO4-. It cannot be in too basic of a solution (greater than 10.5) because then silver hydroxide will form before the silver chromate can form.
Why is it that mohr's method of titration for the determination of halide must be performed in neutral?
When pH is lower than 7, chromic ion gets protonated and chromic acid is predominant in the solution. Consequently, if the pH is above 7, chromate ion concentration is too low to form precipitate with silver ions at the end point. If the pH is above 10, brownish silver hydroxide is formed masking the end point. hence a neutral medium must be maintained
Why is blank titration necessary in the mohr method?
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)
What is the formula of silver chromate?
The chemical formula of silver chromate is Ag2CrO4.
What is Fajan's method of argentometric titration?
Fajan's method of argentometric titration involves the use of potassium chromate as an indicator to detect the end point of a titration between silver ions and chloride ions. The indicator changes color from yellow to red when all the chloride ions have reacted with the silver ions, marking the end point of the titration.
Why is potassium chromate indicater used in silver nitrate titration determining in water chloride?
At the end point, so after all Cl- has reacted with Ag+, a brown-red precipitate of silver chromate (Ag2CrO4), is formed. (Argentometric indicator)Description:The solubility of silver chromate is slightly higher than that of silver chloride. So, in a mixture of both ions silver chloride will be formed. Only when no chloride is left silver chromate will be formed and precipitated out.Prior to the endpoint the solution has a milky lemon yellow appearance, due to the color of the chromate ion and the precipitate of silver chloride already formed.When approaching the endpoint, additions of silver nitrate lead to steadily slower disappearing red colorations. When the red brownish color remains (with grayish spots of silver chloride in it) the endpoint of titration is reached. (wikipedia)
Theory of titration of silver nitrate solution using precipitation and adsorption indicators?
In the titration of silver nitrate solution, a precipitation indicator like chloride ion is used to detect the endpoint through the formation of a white precipitate (AgCl). An adsorption indicator like chromate ion can also be used, where the color change of the adsorbed chromate ion on silver chloride indicates the endpoint. Both indicators are effective in detecting the equivalence point in silver nitrate titrations.
Why mohr titration must be perform at a pH of neutral?
The reaction has to be carried out at neutral conditions because in acid the chromate indicator concentration decreases due to the reaction with the H+ ions, forming HCrO4-. It cannot be in too basic of a solution (greater than 10.5) because then silver hydroxide will form before the silver chromate can form.
Why is argentrometric method called as a mohr method?
The argentometric method is called the Mohr method because it was developed by the German chemist Karl Friedrich Mohr in the 19th century. This titration technique involves the use of silver nitrate as a titrant and is specifically used for the determination of chloride ions in a solution. The method is characterized by the formation of a colored precipitate (silver chromate) at the endpoint, which occurs when all chloride ions have reacted, indicating the completion of the titration.
Iron II chromate?
Iron(II) chromate is a chemical compound with the formula FeCrO4. It is a yellow solid that is sparingly soluble in water. The compound is used in analytical chemistry applications as an indicator for the titration of lead.
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 is it that mohr's method of titration for the determination of halide must be performed in neutral?
When pH is lower than 7, chromic ion gets protonated and chromic acid is predominant in the solution. Consequently, if the pH is above 7, chromate ion concentration is too low to form precipitate with silver ions at the end point. If the pH is above 10, brownish silver hydroxide is formed masking the end point. hence a neutral medium must be maintained
Why mohr method used with cl and br?
The Mohr method is used for the determination of chloride (Cl) and bromide (Br) ions in a solution due to its simplicity and effectiveness in visual titration. It involves the addition of a silver nitrate solution to the sample, which forms a colored precipitate with these halides. The endpoint is indicated by a color change, typically using a chromate indicator that forms a reddish-brown precipitate of silver chromate once all halides are precipitated. This method is advantageous for its accuracy and rapidity in detecting halide concentrations in various samples.
What is the formula for cesium chromate?
Cesium Chromate = Cs2CrO4
What is the formula of silver chromate?
The chemical formula of silver chromate is Ag2CrO4.
What is the formula for Stannic chromate?
Stannic chromate = Tin(IV) chromate = Sn(CrO4)2
