When we mix hydrochloric acid (HCℓ) and sodium hydroxide base (NaOH), a neutralization reaction occurs which can be represented by the following chemical equation:
HCℓ(here) + NaOH(here) → NaCℓ(here) + H2O(ℓ)
This reaction involves chemical substances ionized in an aqueous medium. The acid in question released the H ions in aqueous solution+(here) and Cℓ-(here), and the base released the Na ions+(here) and oh-(here). These ions reacted forming a soluble salt (sodium chloride) and water.
This reaction can then be represented by an ionic equation:
H+(here) + Cℓ-(here) + In+(here) + OH-(here) → NaCℓ(here) + H2O(ℓ)
or
H+(here) + Cℓ-(here) + In+(here) + OH-(here) → In+(here) + Cℓ-(here) + H2O(ℓ)
Thus, the ionic equation is the chemical equation in which ions as well as atoms and molecules appear.
We can also write the ionic equation in a smaller form. For example, in the reaction we are considering, the Na ions+(here) and Cℓ-(here) are called spectator ions and, therefore, can be disregarded in a reduced ionic equation:
H+(here) + OH-(here) → H2O(ℓ)
This type of equation allows you to better visualize the neutralization that has occurred in the system.
Many ionic reactions involve the formation of insoluble salts, that is, of rash. For example, when we mix two aqueous solutions of lead nitrate and sodium iodide, there are ions in the medium that react with each other and form the precipitated lead iodide (a yellow solid).
The chemical equation for this reaction is given by:
Pb (NO3)2(aq) + 2 NaI(here) → PbI2(s) + 2 NaNO3(aq)
The ionic equation and the reduced ionic equation can be represented respectively as follows:
Pb2+(here) + 2 NO3-(here) + 2 In+(here) + 2 I-(here) → PbI2(s) + 2 In+(here) + 2 NO3-(here)
Pb2+(here) 2 I-(here) → PbI2(s)
By Jennifer Fogaça
Graduated in Chemistry
Source: Brazil School - https://brasilescola.uol.com.br/quimica/equacoes-ionicas.htm