The key difference between synthesis reaction and dissociation reaction is that synthesis reaction involves the formation of a new compound via a combination of two or more reactants whereas dissociation reaction involves the breakdown of a compound into two or more components.
Synthesis reaction and dissociation reaction are opposite of each other. The synthesis reaction describes the formation of a new compound while the dissociation reaction describes the breakdown of a compound into its components.
CONTENTS
1. Overview and Key Difference
2. What is a Synthesis Reaction
3. What is a Dissociation Reaction
4. Side by Side Comparison – Synthesis Reaction vs Dissociation Reaction in Tabular Form
5. Summary
What is a Synthesis Reaction?
A synthesis reaction is a type of chemical reaction in which two or more components combine with each other to form a large compound. It is the opposite of the dissociation reaction. It is also called a direct combination reaction as well because it involves the combination of components to form a new compound. In these reactions, the reactants can be either chemical elements or molecules. The product is always a compound or a complex. The general formula for a certain reaction is as follows:
Some examples for synthesis reactions include the combination of hydrogen gas and oxygen gas to form water molecules, the combination of carbon monoxide and oxygen to form carbon dioxide, the combination of aluminium metal and oxygen gas to form aluminium oxide, etc.
The basic feature to recognize a synthesis reaction is that these reactions have a compound formed as the end product form reactants. There, all the atoms present in the reactant molecules have to be present in the end product if it is a synthesis reaction. Moreover, during bond formation, these reactions release energy; therefore, they are exothermic reactions.
What is Dissociation Reaction?
Dissociation reaction is a type of chemical reaction in which one large compound breaks down into its components. It is the opposite of a synthesis reaction. In these reactions, the reactant mostly undergoes ionization (breaks into the ionic components from which the reactant is made of). Therefore, a dissociation reaction can also be named as an ionization reaction. For example, dissociation of a water molecule forms hydroxide ion and hydrogen ion, ionization of hydrochloric acid forms hydrogen ion and chloride anion.
Most dissociation reactions occur in aqueous solutions or water where the compound dissolves by ionization. It happens because the positive and negative ions of the compound are attracted by the positive and negative poles of a water molecule (polarity of water). Moreover, these reactions require energy for the bond-breaking process; thus, they are endothermic reactions.
What is the Difference Between Synthesis Reaction and Dissociation Reaction?
Dissociation reaction is the completely opposite reaction of the synthesis reaction. The key difference between synthesis reaction and dissociation reaction is that synthesis reaction involves the formation of a new compound via the combination of two or more reactants whereas dissociation reaction involves the break down of a compound into two or more components. Usually, synthesis reactions are exothermic reactions because bond formation releases energy while dissociation reactions are endothermic reactions because these reactions require energy for bond breaking. Moreover, the end product of a synthesis reaction is a large compound or a complex but in dissociation reactions, we can observe two or more ionic components as products.
Below infographic summarizes the difference between synthesis reaction and dissociation reaction.
Summary – Synthesis Reaction vs Dissociation Reaction
Dissociation reaction is the completely opposite reaction of synthesis reaction. The key difference between synthesis reaction and dissociation reaction is that synthesis reaction involves the formation of a new compound via the combination of two or more reactants whereas dissociation reaction involves the break apart of a compound into two or more components.
Reference:
1. Helmenstine, Anne Marie. “Dissociation Reaction Definition and Examples.” ThoughtCo, Oct. 21, 2019, Available here.
2. Helmenstine, Anne Marie. “Synthesis Reaction Description Plus Examples.” ThoughtCo, May. 10, 2019, Available here.