Question

IIcat of ncutralization of any strong acid by any strong basc is the same because (1) Basically it is the same reaction taking place in all such cases. (2) Basically it is the reaction of \(\mathrm{H}^{-}+\mathrm{OH} \rightarrow \mathrm{H}_{2} \mathrm{O}\) (3) Strong acids and strong bases ionize completely in water. (4) All the above.

Short answer

All the above (4).

Step-by-step solution

Understand the problem

The exercise requires identifying why the heat of neutralization of any strong acid by any strong base is the same.

Analyze the given options

Review each option to determine if it explains why the heat of neutralization is consistent across different strong acids and bases.

Option 1 Analysis

Option 1 states that it is the same reaction in all cases. This is true because neutralization always forms water and a salt.

Option 2 Analysis

Option 2 specifies the reaction of \(\text{H}^{+}+\text{OH}^{-} \rightarrow \text{H}_{2}\text{O}\). This is accurate and represents the core reaction occurring during neutralization.

Option 3 Analysis

Option 3 mentions that strong acids and strong bases ionize completely in water. Complete ionization ensures that the reaction of \(\text{H}^{+}+\text{OH}^{-} \rightarrow \text{H}_{2}\text{O}\) happens uniformly.

Option 4 Analysis

Option 4 states 'All the above', which combines the explanations from Options 1, 2, and 3. Since all options correctly explain the uniformity in the heat of neutralization, this is the correct choice.

Key concepts

neutralization reaction

Neutralization reactions are chemical reactions where an acid and a base react with each other to form a salt and water. These reactions are fundamental in understanding various chemical processes. During neutralization, the hydrogen ions \((\text{H}^{+})\) from the acid react with the hydroxide ions \((\text{OH}^{-})\) from the base to produce water. For instance, when hydrochloric acid \((\text{HCl})\) reacts with sodium hydroxide \((\text{NaOH})\), the reaction can be represented as: \[ \text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_{2}\text{O} \]
This process is exothermic, meaning it releases heat. The amount of heat released is called the heat of neutralization. For strong acids and bases, the heat of neutralization is almost always the same. This is because the reaction primarily involves \(\text{H}^{+}\) and \(\text{OH}^{-}\) ions forming water.

strong acids and bases

Strong acids and bases are substances that completely dissociate into their ions in water. For example, hydrochloric acid \((\text{HCl})\) is a strong acid, meaning it fully dissociates into \(\text{H}^{+}\) and \(\text{Cl}^{-}\) ions in water. Similarly, sodium hydroxide \((\text{NaOH})\), a strong base, dissociates into \(\text{Na}^{+}\) and \(\text{OH}^{-}\) ions.

• Complete dissociation means that in any solution of a strong acid or base, all the initial molecules break apart into their respective ions.
• This results in a high concentration of \(\text{H}^{+}\) ions in acids and \(\text{OH}^{-}\) ions in bases.
• Because of this uniform dissociation, the reaction between any strong acid and any strong base always involves the same reactants: \(\text{H}^{+}\) and \(\text{OH}^{-}\).

This results in the heat of neutralization for strong acids and bases being remarkably consistent. The energy change remains uniform because the chemical change is essentially the same every time.

complete ionization

Complete ionization refers to the process in which an acid or base completely breaks down into its constituent ions when dissolved in water. In the context of strong acids and bases, this means substances like hydrochloric acid or sodium hydroxide dissociate fully.

• For hydrochloric acid, this means every molecule splits into \(\text{H}^{+}\) and \(\text{Cl}^{-}\) ions.
• In the case of sodium hydroxide, it splits into \(\text{Na}^{+}\) and \(\text{OH}^{-}\) ions.

This complete ionization is crucial for the uniformity of the heat of neutralization. Because all molecules of the acid and base separate into ions, the total reaction is simply \(\text{H}^{+}\) ions meeting \(\text{OH}^{-}\) ions to form water: \[ \text{H}^{+} + \text{OH}^{-} \rightarrow \text{H}_{2}\text{O} \]
This simplicity ensures that the same amount of energy is released each time the reaction occurs, leading to a consistent heat of neutralization for all strong acids and bases.