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

FuseSchool - Global Education
20 Jun 201303:56
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TLDRThe Arrhenius theory of acids and bases defines acids as substances that release H+ ions and bases as those that release OH- ions. However, the Bronsted-Lowry theory expands on this by defining acids as substances that donate H+ ions and bases as those that accept H+ ions. This theory explains why ammonia can act as a base without containing OH- ions, as it accepts H+ ions from water. The concept of amphoteric substances, which can act as either acids or bases, is also introduced. Overall, the Bronsted-Lowry theory focuses on proton transfer in acid-base reactions.

Takeaways
  • 🔬 The Arrhenius theory defines acids as substances that release H+ ions and bases as those that release OH- ions in solution.
  • 🌟 Ammonia (NH3) can act as a base despite not containing OH- ions, challenging the Arrhenius theory.
  • 📚 The Bronsted-Lowry theory expands on the Arrhenius theory by defining acids as proton donors (H+) and bases as proton acceptors.
  • 🧪 Acids can be tested with universal indicator solution or paper, which turns red or orange depending on the acid's strength.
  • 🌈 Blue litmus paper turns red in the presence of an acid, indicating its presence.
  • ⚗️ Hydrochloric acid (HCl) is an example of an acid that dissociates in water to form H+ and Cl- ions.
  • 💧 Water can act as a Bronsted-Lowry base by accepting H+ ions to form the hydronium ion (H3O+).
  • 🔄 The Bronsted-Lowry theory emphasizes the transfer of H+ ions between substances in an acid-base reaction.
  • 🤔 In the case of ammonia dissolving in water, water acts as a Bronsted-Lowry acid by releasing H+ ions, and ammonia acts as a base by accepting them.
  • 🌱 The Bronsted-Lowry definition of acids and bases does not depend on pH or color change indicators but on the ability to donate or accept H+ ions.
  • 🐸 Substances that can act as either an acid or a base, like water, are called amphoteric, similar to how amphibians live in both land and water.
Q & A

  • What is the Arrhenius theory of acids and bases?

    -The Arrhenius theory defines an acid as a substance that releases H+ ions in solution and a base as a substance that releases OH- ions in solution.

  • Why does the Arrhenius theory have limitations when explaining substances like ammonia?

    -The Arrhenius theory has limitations because it only considers substances that release H+ and OH- ions. Ammonia can act as a base without releasing OH- ions, which is not explained by this theory.

  • What is the Bronsted-Lowry theory of acids and bases?

    -The Bronsted-Lowry theory defines an acid as a substance that donates a proton (H+ ion) and a base as a substance that accepts a proton (H+ ion) in solution.

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

    -The Bronsted-Lowry theory expands the concept by not requiring the presence of H+ and OH- ions specifically, but rather focusing on the transfer of protons, which allows for a broader range of substances to be classified as acids or bases.

  • What is the relationship between the pH scale and the strength of an acid?

    -Acids have a pH lower than 7, and the lower the pH, the stronger the acid. The pH scale measures the acidity or alkalinity of a solution.

  • How can we test for the presence of an acid?

    -We can test for acids using a universal indicator solution or paper, which turns red or orange depending on the acid's strength, or blue litmus paper, which turns red in the presence of an acid.

  • What is an example of a reaction involving a Bronsted-Lowry acid and base?

    -An example is the reaction of hydrogen chloride (HCl) dissolving in water to form hydrochloric acid, where HCl dissociates to give a H+ ion and a Cl- ion, with water accepting the H+ ion to form a hydronium ion (H3O+).

  • What is the role of water in the reaction of hydrogen chloride dissolving in water?

    -In the reaction, water acts as a Bronsted-Lowry base by accepting the H+ ion from hydrogen chloride, forming a hydronium ion.

  • How does ammonia act as a base in the context of the Bronsted-Lowry theory?

    -Ammonia acts as a base by accepting a H+ ion from water, forming NH4+ and releasing OH- ions in the process.

  • What is the role of water in the reaction involving ammonia and H+ ions?

    -In the reaction with ammonia, water acts as a Bronsted-Lowry acid by releasing a H+ ion to ammonia.

  • What does it mean for a substance to be amphoteric?

    -A substance is amphoteric if it can act as both an acid and a base, depending on the reaction conditions. This is demonstrated by water, which can act as a base by accepting H+ ions and as an acid by donating them.

  • What is the fundamental process of an acid-base reaction according to the Bronsted-Lowry theory?

    -The fundamental process of an acid-base reaction according to the Bronsted-Lowry theory is the transfer of a proton (H+ ion) from one substance to another.

Outlines
00:00
🔬 Bronsted-Lowry Theory of Acids and Bases

This paragraph introduces the Bronsted-Lowry theory, which expands on the Arrhenius theory by defining acids as substances that donate H+ ions and bases as those that accept H+ ions in solution. It explains how ammonia can act as a base without containing OH- ions and clarifies that the definition of acids and bases in this theory is not dependent on pH. The paragraph also discusses the concept of amphoteric substances, which can act as either an acid or a base, using water as an example. The main focus is on the proton transfer in acid-base reactions.

Mindmap
Keywords
💡Arrhenius Theory
The Arrhenius theory defines acids as substances that release H+ ions and bases as those that release OH- ions in solution. This theory is foundational in understanding the basic properties of acids and bases but has limitations, as it does not account for substances like ammonia that can act as bases without releasing OH- ions. The theory is mentioned in the script to contrast with the Bronsted-Lowry theory, which provides a broader definition of acids and bases.
💡Ammonia (NH3)
Ammonia is highlighted as a substance that can act as a base despite not containing OH- ions, which is a requirement in the Arrhenius theory. In the context of the video, ammonia's ability to accept H+ ions from water demonstrates its basic properties according to the Bronsted-Lowry theory. The script uses ammonia to illustrate the broader concept of bases beyond the Arrhenius definition.
💡Bronsted-Lowry Theory
The Bronsted-Lowry theory expands on the Arrhenius theory by defining acids as substances that donate H+ ions and bases as those that accept H+ ions in solution. This theory is central to the video's theme, as it explains how substances like ammonia can act as bases. The script uses the Bronsted-Lowry theory to demonstrate the transfer of H+ ions in acid-base reactions.
💡pH
pH is a measure of the acidity or basicity of a solution, with a lower pH indicating higher acidity and a higher pH indicating higher basicity. The script mentions that the Bronsted-Lowry definition of acids and bases is not a function of pH, emphasizing that the ability to donate or accept H+ ions is the key characteristic, not the pH level.
💡Universal Indicator
A universal indicator is a tool used to test the acidity or basicity of a solution, changing color in response to the solution's pH. In the script, it is mentioned as a way to test for acids, which turn the indicator red or orange depending on their strength.
💡Hydrochloric Acid (HCl)
Hydrochloric acid is used as an example of an acid in the script. When dissolved in water, it dissociates to form H+ ions and Cl- ions, illustrating the Arrhenius definition of an acid. The script also shows how HCl can further react with water to form a hydronium ion, demonstrating the transfer of H+ ions in a Bronsted-Lowry acid-base reaction.
💡Hydonium Ion (H3O+)
The hydronium ion is formed when water accepts an H+ ion, as shown in the reaction of HCl with water. It is also known as an oxonium ion and is an example of how H+ ions can be transferred in acid-base reactions according to the Bronsted-Lowry theory.
💡H+ Ion Transfer
The transfer of H+ ions is the central process in acid-base reactions according to both the Arrhenius and Bronsted-Lowry theories. The script emphasizes this concept by showing how H+ ions are transferred from an acid to a base, or vice versa, in different reactions.
💡Litmus Paper
Litmus paper is a type of pH indicator that changes color in the presence of acids or bases. The script mentions that blue litmus paper turns red in the presence of an acid, providing a visual test for acidity.
💡Amphoteric
Amphoteric substances can act as either acids or bases, depending on the reaction conditions. The script uses water as an example of an amphoteric substance, which can act as a Bronsted-Lowry acid by releasing H+ ions or as a base by accepting them.
💡Proton
A proton is another term for the H+ ion. The script concludes by emphasizing that an acid-base reaction, according to the Bronsted-Lowry theory, fundamentally involves the transfer of a proton, which is the H+ ion.
Highlights

The Arrhenius theory defines acids as substances that release H+ ions in solution and bases as substances that release OH- ions.

Ammonia (NH3) can act as a base and exhibit alkaline properties without containing OH- ions, challenging the Arrhenius theory.

The Bronsted-Lowry theory of acids and bases addresses gaps in the Arrhenius theory by defining acids as substances that donate H+ ions and bases as substances that accept H+ ions.

Acids are substances with a pH lower than 7 and can be tested using universal indicator solution or paper, which turns red or orange, depending on the strength of the acid.

Blue litmus paper turns red in the presence of an acid, exemplified by hydrochloric acid (HCl).

Hydrogen chloride (HCl) dissolves in water to form hydrochloric acid, dissociating into H+ and Cl- ions.

The H+ ion is transferred to another substance, forming a hydronium ion (H3O+), also known as an oxonium ion.

A Bronsted-Lowry acid releases or donates H+ ions in solution, while a Bronsted-Lowry base accepts H+ ions in solution.

The Bronsted-Lowry definition of acids and bases does not depend on pH levels.

An acid-base reaction, according to the Bronsted-Lowry theory, involves the transfer of an H+ ion from one substance to another.

Ammonia acts as a base in water by accepting an H+ ion, forming NH4+ and OH- ions.

In the ammonia and water reaction, water acts as a Bronsted-Lowry acid by releasing an H+ ion, while ammonia acts as a Bronsted-Lowry base by accepting the H+ ion.

A Bronsted-Lowry base does not need to have a pH greater than 7 or change indicator colors; it only needs to accept H+ ions.

Water (H2O) can act as both an acid and a base in different reactions, making it an amphoteric substance.

Substances that can act as either an acid or a base are termed amphoteric, analogous to amphibians living on land and water.

According to the Bronsted-Lowry theory, an acid dissociates to release or donate H+ ions, and a base accepts H+ ions, making acid-base reactions involve the transfer of a proton.

Transcripts

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Chemistry TheoryAcid BaseArrheniusBronsted-LowryHydrogen IonsAmmonia BaseHydronium IonAcidity TestpH ScaleAmphoteric Substances