Ácidos - Funções inorgânicas - Química

Summary

In this lesson, the focus is on acids, which are inorganic substances that dissolve in water to release hydrogen ions (H+), forming hydronium ions (H3O+). The degree of ionization, called alpha, determines the strength of an acid—strong acids ionize over 50%, moderate acids between 5% and 50%, and weak acids below 5%. Acids are also classified based on the number of hydrogen ions they release, with mono, di, tri, and polyacid categories. Examples include hydrochloric acid (HCl), sulfuric acid (H2SO4), and carbonic acid (H2CO3). The next lesson will cover acid nomenclature.

Takeaways

• 😀 Acids are inorganic substances that are soluble in water and release H+ ions when dissolved.
• 😀 When H+ ions from acids combine with water molecules, they form hydronium ions (H3O+).
• 😀 The presence of hydronium ions in a solution characterizes the substance as an acid.
• 😀 The degree of dissociation of an acid is measured by 'Alpha', which represents the ratio of ionized molecules to the total molecules in solution.
• 😀 If more than 50% of the acid molecules release H+ ions, the acid is classified as a strong acid (e.g., hydrochloric acid, HCl).
• 😀 Acids with an Alpha between 5% and 50% are classified as moderate acids (e.g., hydrofluoric acid).
• 😀 Acids with an Alpha of less than 5% are considered weak acids (e.g., carbonic acid, H2CO3).
• 😀 Acids can also be classified by the number of hydrogen ions they release: monoacidic, diacidic, triacidic, etc.
• 😀 Monoacidic acids release one H+ ion per molecule (e.g., HCl).
• 😀 Triacidic acids release three H+ ions per molecule (e.g., sulfuric acid, H2SO4).
• 😀 In the next lesson, the focus will be on acid nomenclature.

Q & A

What are acids and how are they classified?

Acids are inorganic substances that are soluble in water. When dissolved, they release H+ ions. Acids can be classified based on the degree of ionization into strong, moderate, and weak acids.

What happens when an acid dissolves in water?

When an acid dissolves in water, it releases H+ ions. These ions combine with water molecules, which are polar, to form hydronium ions (H3O+). This is what characterizes an acid in solution.

What is the significance of the hydronium ion in an acidic solution?

The presence of the hydronium ion (H3O+) in a solution is what characterizes a substance as an acid. The hydronium ion is formed when H+ ions from the acid combine with water molecules.

What does the term 'Alfa' refer to in relation to acids?

Alfa refers to the degree of dissociation of an acid, or the percentage of acid molecules that ionize to release H+ ions in a solution. It is calculated by dividing the number of ionized acid molecules by the total number of acid molecules in the solution.

How are acids classified based on their Alfa value?

If Alfa is greater than 50%, the acid is classified as a strong acid. If Alfa is between 5% and 50%, the acid is classified as a moderate acid. If Alfa is less than 5%, the acid is classified as a weak acid.

Can you provide examples of strong, moderate, and weak acids?

Examples of strong acids include hydrochloric acid (HCl) and sulfuric acid (H2SO4). Examples of moderate acids include hydrofluoric acid (HF), while examples of weak acids include carbonic acid (H2CO3) and hydrocyanic acid (HCN).

What is the difference between a monoacidic, diacidic, and triacidic acid?

A monoacidic acid releases one H+ ion per molecule, a diacidic acid releases two H+ ions, and a triacidic acid releases three H+ ions. The classification depends on how many hydrogen ions the acid can release in solution.

How is the classification of acids based on ionizable hydrogen atoms important?

The classification of acids based on the number of ionizable hydrogen atoms helps in determining their strength and behavior in solution. For example, acids that release more than two hydrogen ions (such as sulfuric acid) are classified as polyprotic acids.

What are polyprotic acids?

Polyprotic acids are acids that can release more than one hydrogen ion per molecule. Examples include sulfuric acid (H2SO4), which releases two hydrogen ions, and phosphoric acid (H3PO4), which releases three hydrogen ions.

What topic will be covered in the next lesson related to acids?

In the next lesson, the topic of acid nomenclature will be covered, which involves naming acids based on their chemical composition and properties.