To write the complete ionic equation for the reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl), we start by examining the compounds involved in the reaction.
The balanced molecular equation for this reaction is:
NaOH(aq) + HCl(aq) → H2O(l) + NaCl(aq)
Next, we break down each of the aqueous compounds into their respective ions. Sodium hydroxide and hydrochloric acid dissociate completely in water:
- NaOH(aq) dissociates into Na+(aq) + OH−(aq)
- HCl(aq) dissociates into H+(aq) + Cl−(aq)
- NaCl(aq) dissociates into Na+(aq) + Cl−(aq)
Now we can express the complete ionic equation by substituting the dissociated ions into the balanced equation:
Na+(aq) + OH−(aq) + H+(aq) + Cl−(aq) → H2O(l) + Na+(aq) + Cl−(aq)
At this point, we can see that the sodium ions (Na+) and chloride ions (Cl−) appear on both sides of the equation and are considered spectator ions. To simplify, we can remove these spectator ions:
OH−(aq) + H+(aq) → H2O(l)
Thus, the complete ionic equation for the reaction is:
Na+(aq) + OH−(aq) + H+(aq) + Cl−(aq) → H2O(l) + Na+(aq) + Cl−(aq)
This equation illustrates the ions present in the solution and highlights the reaction that ultimately occurs: the formation of water from hydroxide and hydrogen ions.