沉淀和降水后的差异

Thekey difference在共沉淀和降水之间是coprecipitation,precipitation不希望的化合物与理想化合物的沉淀一起发生，而在沉淀后，在理想化合物沉淀后发生不良化合物的沉淀。

The term precipitation refers to the formation of a solid mass from a solution after treating the solution with some chemicals. Coprecipitation and post precipitation are two types of precipitation process that have both advantages and disadvantages, depending on the situation and purpose of the analysis.

内容

1.Overview and Key Difference
2.What is Coprecipitation
3.What is Post Precipitation
4.Side by Side Comparison – Coprecipitation vs Post Precipitation in Tabular Form
5.概括

What is Coprecipitation?

Coprecipitation is a type of precipitation where soluble compounds in a solution are removed during the course of precipitation. There are three major types of coprecipitation methods. These are the surfaceadsorption, mixed crystal formation, and mechanical entrapment.

Surface adsorption refers to the formation of the precipitate of the undesired compound on the precipitate of the desirable compound as an adsorption process. For example, the formation of coagulatedcolloids; in the reaction between silver nitrate and sodium chloride, the desribale product is the silver chloride precipitate. Here, silver ions form precipitates with other ions present in the solution.

Mixed crystal formation is another type of coprecipitation where the contaminated ion is replaced by an ion-containing crystal. For example, in the precipitation of barium sulfate from barium chloride, coprecipitation of lead sulfate also occurs if the solution contains lead ions. In mechanical entrapment method, undesirable ions get entrapped in the voids of the precipitate that is being formed.

What is Post Precipitation?

降水是一种降水，其中不良化合物的沉淀在理想化合物的沉淀物形成后发生。这种降水发生在第一个沉淀的表面。例如，草酸镁的沉淀后草酸钙的形成。

What is the Difference Between Coprecipitation and Post Precipitation?

Precipitation is the formation of a solid mass from a solution after treating the solution with some chemicals. Coprecipitation is a type of precipitation where soluble compounds in a solution are removed during the course of precipitation. Post precipitation is the precipitation of a second, often related, substance upon the surface of an initial precipitate. So, the key difference between coprecipitation and post precipitation is that in coprecipitation, precipitation of an undesired compound occurs along with the precipitation of the desirable compound whereas, in post precipitation, the precipitation of an undesirable compound occurs after the precipitation of the desirable compound.

Consequently, the contamination from impurities is high in coprecipitation compared to post precipitation. An example for coprecipitation is the precipitation of silver ions with other ions during the silver chloride precipitation; an example for post precipitation is the formation of calcium oxalate after the precipitation of magnesium oxalate.

Below infographic summarizes the difference between coprecipitation and post precipitation.

概括– Coprecipitation vs Post Precipitation

Coprecipitation and post precipitation are two types of precipitation. The key difference between coprecipitation and post precipitation is that in coprecipitation, precipitation of an undesired compound occurs along with the precipitation of the desirable compound whereas, in post precipitation, the precipitation of an undesirable compound occurs after the precipitation of the desirable compound.

Reference:

1. “Gravimetry.” LinkedIn SlideShare, 7 Sept. 2014,Available here.
2.“沉淀和降水后。”Prezi。comAvailable here.
3. Coprecipitation.” Wikipedia, Wikimedia Foundation, 18 Dec. 2019,Available here.

Image Courtesy:

1. “Common Silver Halide Precipitates” By Cychr – I took the photograph after completing the reactions(CC BY 3.0)viaCommons Wikimedia