What Is The Bronsted Lowry Theory | Acids, Bases & Alkali's | Chemistry | FuseSchool

Summary

The Bronsted-Lowry theory expands upon the Arrhenius theory by redefining acids and bases. Acids are now substances that donate H+ ions, while bases are those that accept these ions. This theory explains how ammonia can act as a base without releasing OH- ions, as it accepts H+ from water. Water is identified as amphoteric, capable of acting as both an acid and a base, depending on the reaction. The essence of an acid-base reaction, according to Bronsted-Lowry, is the transfer of a proton (H+).

Takeaways

• 📚 The Arrhenius theory defines acids as substances releasing H+ ions and bases as those releasing OH- ions in solution.
• 🌟 Ammonia (NH3) can act as a base despite not containing OH- ions, challenging the Arrhenius definition.
• 📈 The Bronsted-Lowry theory expands on the Arrhenius theory, focusing on the transfer of H+ ions rather than just their release.
• 🔍 Acids can be detected using universal indicator solutions or papers, which change color based on the acid's strength.
• 💧 In the presence of acids, blue litmus paper turns red, indicating acidity.
• 🌊 Hydrochloric acid (HCl) is an example of an acid, formed when hydrogen chloride gas dissolves in water and dissociates into H+ and Cl- ions.
• 🔄 The H+ ion from HCl transfers to water, forming a hydronium ion (H3O+), also known as an oxonium ion.
• 📌 A Bronsted-Lowry acid donates H+ ions, while a Bronsted-Lowry base accepts them, regardless of pH levels.
• 🤔 Ammonia acts as a base by accepting a H+ ion from water, resulting in the formation of NH4+ and OH- ions.
• 🦈 Water is amphoteric, meaning it can act as both an acid and a base, depending on the reaction.
• 🎯 The essence of an acid-base reaction according to the Bronsted-Lowry theory is the transfer of a proton (H+ ion).

Q & A

What is the main difference between the Arrhenius and Bronsted-Lowry theories of acids and bases?

The Arrhenius theory defines acids as substances that release H+ ions and bases as those that release OH- ions in solution, while the Bronsted-Lowry theory broadens the definition to acids as proton (H+) donors and bases as proton acceptors, regardless of their nature or the presence of H+ or OH- ions.

How does the Bronsted-Lowry theory explain the behavior of ammonia as a base despite not containing OH- ions?

According to the Bronsted-Lowry theory, ammonia acts as a base because it accepts a H+ ion from water, forming NH4+ and releasing OH- as a result of the proton transfer.

What is the significance of the hydronium ion (H3O+) in the context of acid dissociation?

The hydronium ion represents the state where a hydrogen ion (H+) has been transferred to water. In the case of hydrochloric acid dissolving in water, HCl dissociates to form H3O+ and Cl-, where H3O+ is the hydronium ion.

How does the pH level relate to the Arrhenius theory of acids?

In the Arrhenius theory, acids are associated with a pH lower than 7 because they release H+ ions, which lower the pH of the solution.

What is an example of an acid that can be identified using a universal indicator solution or paper?

Hydrochloric acid is an example that can be identified by its ability to turn universal indicator solution red or orange, depending on its strength.

How does the Bronsted-Lowry theory expand the definition of acids and bases compared to the Arrhenius theory?

The Bronsted-Lowry theory allows for a broader definition by focusing on the transfer of protons (H+) rather than the specific release of H+ or OH- ions, thus including reactions where no OH- ions are present.

What is the role of water in the acid-base reaction between ammonia and HCl?

Water acts as a Bronsted-Lowry acid in this reaction by releasing a H+ ion that ammonia accepts, forming NH4+ and OH-.

What term describes substances that can act as either an acid or a base?

Amphiprotic substances can act as either an acid or a base, depending on the reaction context.

How does the concept of amphoteric substances relate to the Bronsted-Lowry theory?

Amphiprotic substances, like water, can both donate and accept protons, thus acting as acids or bases in different reactions according to the Bronsted-Lowry theory.

What is the key aspect of an acid-base reaction according to the Bronsted-Lowry theory?

The key aspect is the transfer of a proton (H+) from one substance to another.

How does the Bronsted-Lowry theory help explain the behavior of substances in acid-base reactions?

It provides a more comprehensive understanding by focusing on the transfer of protons, allowing for the classification of reactions that do not strictly follow the Arrhenius definition of releasing H+ or OH- ions.

What is the significance of the universal indicator solution or paper in identifying acids?

The universal indicator solution or paper changes color in the presence of an acid, indicating its strength by turning red or orange, which helps in identifying and classifying acids.