The molecular equation for the reaction of hydrochloric acid (HCI) and sodium hydroxide (NaOH) is, NaOH (aq.) + HCl (aq.) ?NaCl (aq.) +H2O (I) The net ionic equation is: NaOH(aq.) + HCl (aq.) ?NaCl (aq.) + H2O(I) Na+ (aq.) + OH (aq.) + H+(aq.) + Cl (aq.) ? H2O(l) + Na+ (aq.) + OH-(aq.) none of the above are correct. H+ (aq.) + OH (aq.) ? H2O(1)
The Correct Answer and Explanation is:
The correct answer is: H+ (aq.) + OH- (aq.) → H2O (l).
Explanation:
The reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) is a classic acid-base neutralization reaction. Let’s break it down:
- Molecular Equation:
The molecular equation is: NaOH (aq)+HCl (aq)→NaCl (aq)+H2O (l)\text{NaOH (aq)} + \text{HCl (aq)} \rightarrow \text{NaCl (aq)} + \text{H}_2\text{O (l)}NaOH (aq)+HCl (aq)→NaCl (aq)+H2O (l) This shows the complete chemical reaction, where NaOH and HCl react to form sodium chloride (NaCl) and water (H2O). - Complete Ionic Equation:
When the ionic compounds dissociate in water, we get: Na+(aq)+OH−(aq)+H+(aq)+Cl−(aq)→Na+(aq)+Cl−(aq)+H2O (l)\text{Na}^+ (aq) + \text{OH}^- (aq) + \text{H}^+ (aq) + \text{Cl}^- (aq) \rightarrow \text{Na}^+ (aq) + \text{Cl}^- (aq) + \text{H}_2\text{O (l)}Na+(aq)+OH−(aq)+H+(aq)+Cl−(aq)→Na+(aq)+Cl−(aq)+H2O (l) In the complete ionic equation, sodium (Na+) and chloride (Cl-) ions are spectator ions. They do not participate in the actual neutralization reaction. - Net Ionic Equation:
The net ionic equation eliminates the spectator ions (Na+ and Cl-) to focus on the species that actually react. Since Na+ and Cl- are unchanged on both sides of the equation, they are omitted. What remains is: H+(aq)+OH−(aq)→H2O (l)\text{H}^+ (aq) + \text{OH}^- (aq) \rightarrow \text{H}_2\text{O (l)}H+(aq)+OH−(aq)→H2O (l) This is the net ionic equation for the reaction, showing that hydrogen ions (H+) from the acid and hydroxide ions (OH-) from the base combine to form water.
Why the Other Choices are Incorrect:
- Option 1 (NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)): This is the molecular equation, not the net ionic equation.
- Option 2 (Na+ (aq) + OH- (aq) + H+ (aq) + Cl- (aq) → H2O(l) + Na+ (aq) + OH-(aq)): This is the complete ionic equation, but not the net ionic equation. It still contains the spectator ions Na+ and Cl-.
- Option 3 (None of the above): Since option 4 is correct, this option is incorrect.
In conclusion, the net ionic equation for the neutralization of HCl and NaOH is simply the combination of H+ and OH- to form water.
