Question

What is a solid-state reaction?

Answer 1

Solid-state reactions are performed where solvents are absent. It is a mechanochemical reaction. There is not much contact between the reactants. The reactants have limited access to each other. The reactions are performed to obtain polycrystalline inorganic solids from the solid reagents.

Complete answer:
Solid-state reactions are the reactions that are performed in the absence of solvents. The reaction is mechanochemical. In this reaction, the starting material is either ground or melted or simply heat is applied to a mixture of starting material. These reactions are done to obtain polycrystalline inorganic solids from solid reagents. At room temperature solids do not react with each other, and so for the reaction to occur at an appreciable rate, they are heated at a very high temperature of about $1000 - {1500^0}C$ . Sometimes it is also used in organic synthesis. The solid-state reaction is also called a dry media reaction or a solventless reaction. Solid-state reaction sintering of metal powder mixtures is a way to produce alloys such as carbon steel, Fe-Ni, Fe-Mn, and many more.
Factors that affect solid-state reaction are chemical and morphological properties of the reagents including the reactivity, surface area, and free energy change with the solid-state reaction, and other reaction conditions, such as the temperature, pressure, and the environment of the reaction.

Note:
When the solid-state reactions are carried out there is not much wastage of chemicals, the yields of these reactions are very high and also the costs of these reactions are very low. The reaction is very environmentally friendly. However, it has certain disadvantages also. There can be the formation of toxic waste products. It is not suitable for mass production.