Difference Between Agglutination and Precipitation

Main Difference – Agglutination vs Precipitation

Both agglutination and precipitation refer to the formation of a solid mass inside a solution. This formed solid mass will either stay as a suspension or sink to the bottom of the container if it is denser than the solution. However, it is insoluble in that solution. The main difference between agglutination and precipitation is that agglutination is the formation of a solid mass by aggregating suspended particles in a solution whereas precipitation is the formation of a solid mass as a result of a chemical reaction that occurs between two ionic components.

Key Areas Covered

1. What is Agglutination
      – Definition, Formation, Uses
2. What is Precipitation
     – Definition, Formation, Uses
3. What is the difference between Agglutination and Precipitation
      – Comparison of Key Differences

Key Terms: Agglutination, Aggregate, Blood grouping, Precipitation, Precipitate, Precipitant, Solution

What is Agglutination?

Agglutination is the aggregation of particles to form a single large solid mass. This mass will either stay as a suspension or will sink to the bottom of the container. The end product is called the aggregate. Agglutination occurs with particles which are already present in the solution.

The best example for agglutination comes from biology, in the formation of visible aggregates of antibody-antigen complexes. This is very important in blood grouping because the matching blood group should be given to a person in blood transfusions. If the wrong blood group is given, it will cause clump formation of red blood cells since antibodies react with the blood cells, forming in clumps.

Figure 1: Antibody-Antigen Complex

What is Precipitation?

Precipitation is the formation of an insoluble molecule in a liquid solution; this insoluble molecule is called the precipitate. A precipitate is formed when two soluble ionic compounds are mixed. Soluble ionic compounds can break into their ions in the solution. Then these ions can react with each other to form a precipitate or stay as a solubilized ion in that solution. The chemical species that cause this precipitation is called precipitant.

In addition, precipitates can form when the temperature of the solution is lowered. The low temperature reduces the solubility of salts, causing them to precipitate in the solution. The formed precipitate may stay as a suspension in the solution if there isn’t sufficient gravity. But later on, the precipitate particles will sediment to the bottom of the container unless disturbed.

Precipitation is a very important phenomenon since the formed precipitate is visible. The formation of a precipitate can indicate the presence of a chemical reaction. For example, the reaction between silver nitrate (AgNO₃) and sodium chloride (NaCl) will form a white precipitate of silver chloride (AgCl).

Figure 2: Suspension and Precipitation

Difference Between Agglutination and Precipitation

Definition

Agglutination: Agglutination is the process of forming a solid mass from particles present in a solution.

Precipitation: Precipitation is the process of forming insoluble solid mass from the reaction of ions present in a solution.

Raw Material

Agglutination: The starting material for agglutination are the particles present in the solution.

Precipitation: The starting material for precipitation are ions present in a solution.

Type of Reaction

Agglutination: Agglutination involves complex, forming reactions.

Precipitation: Precipitation involves chemical reactions between salts or ionic compounds.

End Product

Agglutination: The formed solid mass usually sink to the bottom of the container.

Precipitation: The precipitate will either stay as a suspension or sink to the bottom of the container as influenced by the gravity.

Uses

Agglutination: Agglutination is useful in blood grouping.

Precipitation: Precipitation is useful in quantitative analysis, pigment formation, and water treatment techniques.

Conclusion

Agglutination and precipitation are used as detection methods for a number of inorganic and biological analysis. Precipitation is very important in chemical terms whereas agglutination is useful in biological terms. Although the final outcome is the same for both agglutination and precipitation, these are distinguishable in their processes. The main difference between agglutination and precipitation is that agglutination is the formation of a solid mass by aggregating suspended particles in solution whereas precipitation is the formation of a solid mass as a result of a chemical reaction occur between two ionic components.

References:

1.”Precipitation Reactions.” Chemistry LibreTexts. Libretexts, 27 Aug. 2016. Web. Available here. 09 June 2017. 
2.”Precipitation Reactions – Boundless Open Textbook.” Boundless. Boundless, 13 Aug. 2016. Web. Available here. 09 June 2017. 
3. Raniaaboshady Follow. “Agglutination.” LinkedIn SlideShare. N.p., 13 Sept. 2014. Web. Available here. 09 June 2017. 

Image Courtesy:

1. “Antigen-antibody-complex” By Alejandro Porto – Basada en File:IgM scheme.svg de WarX. (CC BY-SA 3.0) via Commons Wikimedia
2. “Chemical precipitation diagram” By Vectorized by ZooFari; raster by ZabMilenko – Own work, Chemical precipitation diagram.png (Public Domain) via Commons Wikimedia