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This method uses a back titration with potassium thiocyanate to determine the concentration of chloride ions in a solution.
Before the titration an excess volume of a standardized silver nitrate solution is added to the solution containing chloride ions, forming a precipitate of silver chloride (AgCl). The term 'excess' is used as the moles of silver nitrate added are known to exceed the moles of sodium chloride present in the sample so that all the chloride ions present will react.
Ag+ + Cl- AgCl(s) (Ksp = 1.70 × 10−10)
Excess White
Excess of Ag+ is back titrated with SCN-.
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ReneBack titration is used in the Volhard method when the analyte interferes with the primary titration method. This allows for the determination of the interfering substance before the main titration is carried out. It provides more accurate results by isolating the interfering substance and ensuring that it does not affect the primary titration.
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What is a volhard method?
The Volhard method is a chemical titration method used to determine the concentration of halide ions, such as chloride, bromide, or iodide, in a sample. It involves adding a silver nitrate solution to the sample to form a precipitate, which is then back-titrated with a standard solution of thiocyanate ion to determine the halide concentration.
What is a back titration?
A back titration is a technique used in analytical chemistry to determine the concentration of an analyte by reacting it with an excess of a known reagent, then back-titrating the remaining excess reagent. This method is useful when the analyte reacts slowly or incompletely with the titrant in a direct titration.
What are the two indirect method of titration?
The two indirect methods of titration are back titration and reverse titration. In back titration, an excess of a reagent is added to react with the analyte, and then the unreacted excess is titrated to determine the amount that reacted with the analyte. In reverse titration, a standard solution is first added to a known amount of analyte to react completely, and then the excess standard solution is titrated back to determine the amount that reacted with the analyte.
What are complexometric titration method?
Complexometric titration is a type of volumetric analysis used to determine the concentration of metal ions in a solution by forming complexes with a specific reagent. In this method, a chelating agent is typically used to form a stable complex with the metal ion, and the endpoint of the titration is usually determined using a colorimetric indicator or a pH meter. This technique is commonly employed in the analysis of a variety of metal ions in solution.
Does it take more NaOH in back titration with phenolphthalein?
Yes, it takes more NaOH in a back titration with phenolphthalein compared to a direct titration because the indicator reacts with the excess acid in the sample before the endpoint is reached. This means more base is required to neutralize the excess acid present.
