Chapter 7: Problem 3
In water the acids \(\mathrm{HClO}_{4}, \mathrm{HCl}, \mathrm{H}_{2} \mathrm{SO}_{4}\) and \(\mathrm{HNO}_{3}\) exhibit the same strength as they are completely ionized in water (a base). This is called .......... of the solvent water. (1) Strength (2) Capacity (3) Buffer effect (4) Lcvelling cffect
Short Answer
Expert verified
The correct term is 'leveling effect'.
Step by step solution
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Acid Ionization
When an acid dissolves in a solvent like water, it breaks up into ions. This is called acid ionization.
The extent of ionization depends on the type of acid and the nature of the solvent.
Strong acids, such as \(\text{HClO}_4\), \(\text{HCl}\), \(\text{H}_2\text{SO}_4\), and \(\text{HNO}_3\), ionize completely in water.
This means all acid molecules dissociate into protons (\(\text{H}^+\)) and their corresponding anions (negative ions).
For instance:
Weak acids, on the other hand, only partially ionize in water. That means, only some of the acid molecules dissociate, and an equilibrium is established between the ionized and non-ionized forms.
It’s important to understand that ionization is crucial for determining the behavior and reactivity of acids in various solvents.
The extent of ionization depends on the type of acid and the nature of the solvent.
Strong acids, such as \(\text{HClO}_4\), \(\text{HCl}\), \(\text{H}_2\text{SO}_4\), and \(\text{HNO}_3\), ionize completely in water.
This means all acid molecules dissociate into protons (\(\text{H}^+\)) and their corresponding anions (negative ions).
For instance:
- \(\text{HCl} \rightarrow \text{H}^+ + \text{Cl}^-\)
- \(\text{H}_2\text{SO}_4 \rightarrow 2\text{H}^+ + \text{SO}_4^{2-}\)
Weak acids, on the other hand, only partially ionize in water. That means, only some of the acid molecules dissociate, and an equilibrium is established between the ionized and non-ionized forms.
It’s important to understand that ionization is crucial for determining the behavior and reactivity of acids in various solvents.
Strength of Acids
The strength of an acid is a measure of its ability to donate protons (\(\text{H}^+\)).
Strong acids completely ionize in a solvent, while weak acids only partially ionize.
Here’s why this distinction matters:
In water, the four acids mentioned—\(\text{HClO}_4\), \(\text{HCl}\), \(\text{H}_2\text{SO}_4\), and \(\text{HNO}_3\)—behave as equally strong acids because they completely ionize.
This phenomenon, where different acids exhibit the same strength when fully ionized in a solvent, is known as the leveling effect.
Presenting their strength identically simplifies comparing their behaviors in aqueous solutions.
Strong acids completely ionize in a solvent, while weak acids only partially ionize.
Here’s why this distinction matters:
- For strong acids, since all molecules dissociate, the concentration of protons is high. This makes them highly reactive.
- With weak acids, fewer molecules donate protons, resulting in a lower concentration of protons. This makes them less reactive.
In water, the four acids mentioned—\(\text{HClO}_4\), \(\text{HCl}\), \(\text{H}_2\text{SO}_4\), and \(\text{HNO}_3\)—behave as equally strong acids because they completely ionize.
This phenomenon, where different acids exhibit the same strength when fully ionized in a solvent, is known as the leveling effect.
Presenting their strength identically simplifies comparing their behaviors in aqueous solutions.
Solvent Properties
The properties of the solvent play a crucial role in the behavior of acids.
Solvents can influence the extent of ionization and, consequently, the strength of acids.
Here’s how:
**Dielectric constant:** This measures a solvent’s ability to reduce the electrostatic forces between charged particles. Solvents with a high dielectric constant, like water, facilitate ionization because they stabilize the resulting ions.
**Protic vs. Aprotic Solvents:** Protic solvents, like water, have hydrogen atoms that can form hydrogen bonds. This characteristic helps stabilize the ions produced when acids ionize. Aprotic solvents, on the other hand, do not have hydrogen atoms available for bonding and are less effective at stabilizing ions.
The **leveling effect** specifically refers to how a solvent like water makes all strong acids exhibit the same apparent strength by completely ionizing them.
As a result, you cannot distinguish between the strengths of different strong acids when dissolved in water because they all look equally strong.
Solvents can influence the extent of ionization and, consequently, the strength of acids.
Here’s how:
**Dielectric constant:** This measures a solvent’s ability to reduce the electrostatic forces between charged particles. Solvents with a high dielectric constant, like water, facilitate ionization because they stabilize the resulting ions.
**Protic vs. Aprotic Solvents:** Protic solvents, like water, have hydrogen atoms that can form hydrogen bonds. This characteristic helps stabilize the ions produced when acids ionize. Aprotic solvents, on the other hand, do not have hydrogen atoms available for bonding and are less effective at stabilizing ions.
The **leveling effect** specifically refers to how a solvent like water makes all strong acids exhibit the same apparent strength by completely ionizing them.
As a result, you cannot distinguish between the strengths of different strong acids when dissolved in water because they all look equally strong.
