Question

Hydrochloric acid is a stronger acid than acetic acid because (1) It can neutralize large quantity of alkali. (2) It can corrode anything it comes in contact. (3) It ionizes completely into ions in an aqueous solution. (4) It ionizes partially into ions in aqueous solution.

Short answer

Option (3) - It ionizes completely into ions in an aqueous solution.

Step-by-step solution

- Understand the Question

Read the question thoroughly to understand what is being asked. The question is asking why Hydrochloric acid is a stronger acid than acetic acid.

- Recall the Definition of Acid Strength

Recall that the strength of an acid is determined by its ability to completely ionize in an aqueous solution. A stronger acid ionizes more completely.

- Evaluate Each Option

Evaluate each answer option to determine which one aligns with the definition of a strong acid: 1. Neutralizing a large quantity of alkali does not define acid strength. 2. Corrosiveness also does not determine strength. 3. Complete ionization in an aqueous solution describes a strong acid. 4. Partial ionization describes a weak acid.

- Select the Correct Answer

Given the evaluation, option (3) 'It ionizes completely into ions in an aqueous solution' is the reason why Hydrochloric acid is stronger than acetic acid.

Key concepts

ionization

Ionization refers to the process in which a molecule splits into ions when mixed with a solvent, typically water. This splitting allows the substance to participate more readily in chemical reactions.
For instance, when hydrochloric acid (HCl) is dissolved in water, it ionizes completely into hydrogen ions (H⁺) and chloride ions (Cl^-).
Acetic acid (CH₃COOH), on the other hand, only partially ionizes when in water. This results in fewer available hydrogen ions for reactions.
Complete ionization is what makes hydrochloric acid a strong acid, while partial ionization is why acetic acid is considered a weak acid.

• Important takeaway: ionization extent directly affects acid strength.

aqueous solution

An aqueous solution is simply a solution where water acts as the solvent.
When an acid dissolves in water, it forms an aqueous solution, which allows the acid to ionize.
For example, when HCl is added to water, it forms an aqueous hydrochloric acid solution, where HCl dissociates completely into ions.
This complete ionization helps increase the solution's conductivity and its acidic properties.
Acetic acid in water forms an aqueous acetic acid solution but only partially separates into ions, resulting in lower conductivity.

• Important takeaway: The nature of the aqueous solution affects how completely an acid can ionize.

strong acid

A strong acid is just an acid that completely ionizes in water, meaning it fully breaks up into ions.
This is key because the more an acid ionizes, the more hydrogen ions are released, making the solution more acidic.
Examples of strong acids include hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and nitric acid (HNO₃).
In contrast, acetic acid is a weak acid because it does not completely ionize in water.

• Important takeaway: The extent of ionization determines if an acid is strong or weak.