What is the Difference Between Synthesis and Decomposition

The main difference between synthesis and decomposition is that two or more simple substances combine to form a more complex product in synthesis, whereas reactants yield two or more products in decomposition.

Synthesis and decomposition are two chemical reaction types. Redox reactions and precipitation reactions are the other two types of chemical reactions.     

Key Areas Covered

1. What is Synthesis
– Definition, Features, Importance
2. What is Decomposition
– Definition, Features, Importance
3. Similarities Between Synthesis and Decomposition
– Outline of Common Features
4. Difference Between Synthesis and Decomposition
– Comparison of Key Differences

Key Terms 

Synthesis, Decomposition 

Difference Between Synthesis and Decomposition - Comparison Summary

What is Synthesis

Synthesis is a chemical reaction that combines two elements to make a product. It is a complex chemical compound, while the reactants can also be simple. Also, certain conditions are important for the occurrence of the reaction. In addition, reactions require mixing in a reaction vessel, a simple round bottom flask, or a chemical reactor. On the other hand, producing the final complex compound may require several steps. Also, it may form one or more complex compounds at the end of the reaction. However, reaction yield is the amount of complex chemical compounds formed. It can be expressed in grams or as a percentage of the total quantity. Meanwhile, unwanted chemical reactions that can occur in the settings are called side reactions. They reduce the desired yield.

Compare Synthesis and Decomposition

Figure 1: Inorganic Synthesis

Furthermore, organic and inorganic synthesis are the two synthesis types. Organic synthesis produces organic compounds. Also, when organic synthesis starts from basic compounds in the laboratory, it is a purely synthetic process. But semisynthetic organic synthesis is the chemical synthesis starting from plants and animals. In contrast, inorganic synthesis produces inorganic compounds such as anti-cancer drugs.

What is Decomposition

Decomposition is a chemical reaction in which the reactants produce more than one chemical compound as the product. Therefore, it is the breakdown of a complex chemical compound into several simple compounds. However, the breaking down of a complex chemical compound requires energy. Therefore, decomposition reactions are endothermic. Higher temperatures can accelerate the decomposition reactions. Also, the exposure of chemical compounds to extreme environmental conditions such as heat, humidity, radiation, or acidity reduces the stability. However, the three types of decomposition reactions are thermal, electrolytic, and photolytic decomposition.

Synthesis vs Decomposition

Figure 2: Electrolysis of Water

Moreover, decomposition is the opposite of chemical synthesis. Often, it is an undesired type of chemical reaction. However, it is a desired chemical reaction in waste treatment processes. In addition, several analytical techniques, including traditional gravimetric analysis, thermogravimetric analysis, and mass spectroscopy, use decomposition reactions.  

Similarities Between Synthesis and Decomposition

  • Synthesis and decomposition are two chemical reaction types.
  • They produce one or more products by reacting two or more reactants. 

Difference Between Synthesis and Decomposition


Synthesis refers to the construction of complex chemical compounds from simpler ones. In contrast, decomposition refers to a chemical reaction in which one reactant breaks down into two or more products.

Type of Reaction

Synthesis is forming a complex product, while decomposition is breaking a complex compound into simple compounds. 

Chemical Bonds

Synthesis forms chemical bonds, while decomposition breaks down chemical bonds.


Synthesis releases energy, while decomposition requires energy.


Burning charcoal in excess oxygen for carbon dioxide production is an example of synthesis, while the thermal decomposition of limestone is an example of a decomposition reaction.


In brief, synthesis and decomposition are two chemical reactions that occur between chemical compounds. Synthesis is the formation of chemical compounds by reacting two or more chemical substances. It forms new chemical bonds, releasing energy. The formation of carbon dioxide by burning charcoal in excess oxygen is an example of a synthesis reaction. In comparison, decomposition breaks down chemical bonds, forming two or more chemical compounds. However, it requires energy. The thermal decomposition of limestones is an example of a decomposition reaction. Therefore, the main difference between synthesis and decomposition is the chemical bond formation or breaking down. 

  1. Synthesis. Department of Chemistry. (n.d.). 
  2. Decomposition reaction: Definition, examples, & applications. Chemistry Learner. (2023, August 11). 
Image Courtesy:
  1. Cisplatin synthesis” By Anypodetos – Own work (CC0) via Commons Wikimedia
  2. Electrolysis of Water” By JSquish – Own Work (CC-BY SA 3.0) via Commons Wikimedia

About the Author: Lakna

Lakna, a graduate in Molecular Biology and Biochemistry, is a Molecular Biologist and has a broad and keen interest in the discovery of nature related things. She has a keen interest in writing articles regarding science.

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