In 1903, a scientist named Svante Arrhenius won the Nobel Prize for his work on electrolytes and ions in water. He came up with a theory about acids and bases. Later, Johannes Nicolaus Brønsted and Thomas Martin Lowry built on his work to create a new definition of acid and base. They named it the Brønsted-Lowry theory of acids and bases.

So, what are Brønsted-Lowry acids and bases? These are substances that either donate or accept hydrogen ions in a chemical reaction. Acids are substances that donate hydrogen ions, while bases are substances that accept them. Here are some examples of Brønsted-Lowry acids and bases:

Acids: Hydrochloric acid, acetic acid, sulfuric acid.
Bases: Ammonia, sodium hydroxide, water.

When Brønsted-Lowry acids and bases react, they can create what's called a conjugate acid-base pair. This is where the acid donates a hydrogen ion to the base, creating a conjugate base. The base then accepts the hydrogen ion, creating a conjugate acid. By understanding Brønsted-Lowry acids and bases, we can better understand chemical reactions and how substances interact with each other.

Brønsted-Lowry theory of acids and bases

According to the Brønsted-Lowry theory, an acid is any species that reacts by releasing a proton, while a base is a species that reacts by taking up a proton. This still fits in with Arrhenius’ theory - for example, in solution an acid reacts with water by giving a proton to it. Water can behave as both an acid and a base, and is therefore considered an amphoteric substance.

Examples of Brønsted-Lowry acids and bases

Brønsted-Lowry acids and bases always react in pairs, with the general equation being:

acid + base ⇌ conjugate acid + conjugate base

This means that one substance donates a proton, while the other accepts it. Some common examples of Brønsted-Lowry acids and bases include:

Acids: Hydrochloric acid, sulfuric acid, acetic acid.
Bases: Ammonia, sodium hydroxide, water.

It's important to note that you'll never find a hydrogen ion by itself - it will always be reacting with some sort of base. Similarly, you'll never find just an acid by itself - it will always be reacting with a base to form a conjugate acid and conjugate base.

Conjugate acids and bases

Brønsted-Lowry theory explains that when an acid and a base react, they produce conjugate acid and conjugate base. A conjugate acid is a base that has accepted a proton from an acid, while a conjugate base is an acid that has donated a proton to a base. Every acid has a conjugate base, and every base has a conjugate acid. Conjugate pairs behave just like any other acid or base.

The strength of an acid or base affects the strength of its conjugate partner. A stronger acid will have a weaker conjugate base, and a stronger base will have a weaker conjugate acid.

Neutralization reactions are a type of reaction between an acid and a base, which produce a salt and often water. Examples of neutralization reactions include acid + hydroxide, acid + carbonate, and acid + ammonia. The resulting salt is an ionic compound consisting of positive and negative ions held together in a lattice structure.

Acid + hydroxide

Hydroxides belong to a special category of bases known as alkalis. Alkalis are bases that can dissolve in water. It's important to note that not all bases are alkalis, but all alkalis are bases.

When an acid reacts with a hydroxide, it produces a salt and water. For instance, the reaction between hydrochloric acid and sodium hydroxide produces sodium chloride and water. This reaction is known as a neutralization reaction, and it can be represented as:

HCl + NaOH → NaCl + H2O

In this reaction, HCl is the acid, NaOH is the alkali, NaCl is the salt, and H2O is the water. The salt formed in this reaction is an ionic compound made up of positive and negative ions held together in a lattice structure.

Overall, the reaction between an acid and an alkali produces a salt and water, and it's an example of a neutralization reaction.

Acid + carbonate

Acids react with carbonates to give a salt, water and carbon dioxide. For example, if you react sulfuric acid (H2SO4) with magnesium carbonate (MgCO3), you produce the salt magnesium sulfate (MgSO4):

Acid + ammonia

When an acid reacts with ammonia (NH3), it produces an ammonium salt, such as ammonium ethanoate (CH3COO-NH4+). Although it may not seem like it at first, water is actually produced in this reaction.

In solution, ammonia molecules react with water to form ammonium hydroxide (NH4OH). When acid is added to the solution, the ammonium hydroxide ions react with the acid to produce an ammonium salt and water.

The reaction between ammonia and hydrochloric acid involves two steps, with the second step producing water. When the equations for both steps are combined, the water molecules cancel out, and we are left with the equation for the overall reaction.

In solution, acids and bases ionize, which means they lose or gain electrons to form a charged species. When sodium hydroxide and hydrochloric acid react, they ionize to form hydronium ions (H3O+), chloride ions (Cl-), hydroxide ions, and sodium ions. These ions then react to produce a salt and water. One of the water molecules cancels out when the equations are combined. Overall, neutralization reactions occur because acids and bases ionize in solution, and their ions react with each other to produce a salt and water.

The Brønsted-Lowry theory defines an acid as a proton donor and a base as a proton acceptor. Common examples of acids include HCl, H2SO4, HNO3, and CH3COOH, while common bases include NaOH, KOH, and NH3.

When an acid donates a proton, it produces a conjugate base, and when a base accepts a proton, it produces a conjugate acid. These two substances are known as conjugate pairs.

An amphoteric substance is a species that can act as both an acid and a base. This means that it can donate a proton in the presence of a stronger base or accept a proton in the presence of a stronger acid.

A neutralization reaction occurs when an acid and a base react to produce a salt and often water. This type of reaction is commonly used in everyday life, for example in the neutralization of stomach acid with an antacid tablet.

Overall, the Brønsted-Lowry theory provides a fundamental understanding of acids and bases and their behavior in chemical reactions.

Brønsted-Lowry Acids and Bases

What are Brønsted-Lowry acids and bases?

A Brønsted-Lowry acid is a proton donor whilst a Brønsted-Lowry base is a proton acceptor.

What are examples of Brønsted-Lowry acids and bases?

Brønsted-Lowry acids include hydrochloric acid, sulfuric acid and ethanoic acid. Brønsted-Lowry bases include sodium hydroxide and ammonia.

What is a Brønsted-Lowry conjugate acid-base pair?

A conjugate base is an acid that has lost a proton and a conjugate acid is a base that has accepted a proton. All acids form conjugate bases when they react and all bases form conjugate acids. Therefore, acids and bases all come with a paired conjugate base or acid respectively. For example, the conjugate base of the hydrochloric acid is the chloride ion.

What is meant by a Brønsted-Lowry acid?

A Brønsted-Lowry acid is a proton donor.

How do you identify Brønsted-Lowry acids and bases?

You identify Brønsted-Lowry acids and bases by considering their reactions with other species. Brønsted-Lowry acids lose a proton, whilst Brønsted-Lowry bases gain a proton.

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