A net ionic equation shows only the substances that directly participate in a chemical reaction in an electrolyte solution, omitting non-participating ions called spectator ions. It simplifies the reaction to show only the actual reaction taking place.
A net ionic equation is a form of chemical equation in which substances are represented by their ionic formulas and only those substances that directly participate in the chemical reaction are included. This type of equation is usually used to show the reactions of chemical compounds that exist in an aqueous or liquid solution called an electrolyte. Electrolytes are substances made up of free-floating ions, positively or negatively charged atoms that enable the solution to conduct electricity. Some of the ions in an electrolyte can react with each other to form a product, while other ions remain in the solution and do not participate in the reaction. A net ion equation eliminates non-participating ions and shows only the ions that change into a different product over the course of the reaction.
In a general chemical equation, substances are represented by their full chemical formulas – for example, the reaction of aqueous solutions (aq) of sodium hydroxide (NaOH) and hydrochloric acid (HCl) would be shown as NaOH (aq) + HCl (aq). ), followed by an arrow and the product formulas, indicating what the reaction would produce. In reality, however, both sodium hydroxide and hydrochloric acid are strong electrolytes, meaning they completely dissociate into their constituent ions when in solution. Sodium hydroxide does not exist as a NaOH molecule in solution, it exists as a positively charged sodium ion (Na+) and a negatively charged hydroxide ion (OH-), both floating freely in the mixture. An ion equation would therefore show strong electrolytes as individual ions with either positive or negative charges. Non-electrolyte substances that have not dissociated into ions would remain written in molecular form.
The net ionic equation goes further. Instead of simply representing all separate ions and their products in the equation, it omits the ions that do not change during the reaction. These non-participating ions are called spectator ions. Simplifying the reaction in this way, a net ion equation shows only the actual reaction taking place.
For example, in the above-mentioned reaction of sodium hydroxide and hydrochloric acid, a pure liquid product (l), water (H2O), is formed. A water molecule consists of two hydrogen atoms bonded to one oxygen atom. In the water product, the single oxygen atom and one of the hydrogen atoms both come from the hydroxide ion (OH-) of sodium hydroxide, while the second hydrogen atom is the hydrogen ion (H+) of hydrochloric acid. Because OH- and H+ ions change shape and bond to create liquid water, they are included in the net ion equation.
The sodium ion (Na+) from sodium hydroxide (NaOH) and the chlorine ion (Cl-) from hydrochloric acid (HCl), however, do not interact to create the final product. At the end of the reaction, there are still free ions in the solution. Sodium and chlorine are therefore the spectator ions of this reaction, and are not included in the net ion equation. The net ionic equation in the reaction described above should read OH-(aq) + H+(aq) –> H2O(l).
Protect your devices with Threat Protection by NordVPN
