Question

What is the conjugate acid of \(\mathrm{H}_{2} \mathrm{O}\) ? of \(\mathrm{NH}_{3}\) ?

Short answer

The conjugate acid of H₂O is H₃O⁺, and of NH₃ is NH₄⁺.

Step-by-step solution

Understanding Conjugate Acids

A conjugate acid is formed when a base receives a proton (H⁺ ion). In this case, we need to find what products are formed when the molecules H₂O and NH₃ each receive one proton.

Conjugate Acid of Water

Begin by knowing that water (H₂O) acts as a base by accepting a proton (H⁺) to form its conjugate acid. When H₂O receives an additional H⁺, it becomes H₃O⁺ (hydronium ion).

Conjugate Acid of Ammonia

Now, consider ammonia (NH₃) acting as a base by accepting a proton (H⁺). When NH₃ receives an H⁺, it becomes NH₄⁺ (ammonium ion).

Verify Results

Check both transformations to ensure they meet the definition of forming a conjugate acid by proton addition. H₂O + H⁺ → H₃O⁺ and NH₃ + H⁺ → NH₄⁺ both correctly show the base receiving a proton to form a conjugate acid.

Key concepts

Proton Addition

Proton addition is a fundamental concept in chemistry that describes the process of adding a proton (H⁺) to a molecule. This process plays a crucial role in forming conjugate acids. Imagine a proton as a small, positively charged particle that seeks to bond with a neutral or negatively charged molecule. When a base encounters this proton, it undergoes protonation.

During proton addition:

• The base gains a proton to form a conjugate acid.
• This interaction can be depicted through chemical equations like H₂O + H⁺ → H₃O⁺.
• It results in stronger bonds within the molecule due to the new proton attachment.

Proton addition is also reversible. This means that conjugate acids can release the proton back, functioning as an acid in different reactions.

Water Chemistry

Water chemistry encompasses various chemical properties and reactions involving water. Water (H₂O) is a versatile compound and can act both as an acid and a base

• In its role as a base, water accepts a proton to form the hydronium ion (H₃O⁺).
• Inversely, when acting as an acid, water can donate a proton to form hydroxide ion (OH⁻).

This dual ability is central to understanding pH levels and acid-base reactions.

Consider the reaction: H₂O + H⁺ → H₃O⁺. Here, water accepts a proton and chemically transforms into the hydronium ion. This reaction showcases the importance of water's role in countless chemical processes.

Acid-Base Reactions

Acid-base reactions are chemical reactions that involve the transfer of protons between a donor (acid) and an acceptor (base). This interchange is a central theme in chemistry, setting the foundation for many biological and chemical processes.

In these reactions:

• An acid donates a proton, becoming its conjugate base.
• A base accepts a proton, becoming its conjugate acid.

An excellent example is the formation of NH₄⁺ from NH₃: NH₃ + H⁺ → NH₄⁺. Here, ammonia acts as a base as it accepts a proton to form the ammonium ion, its conjugate acid.

The understanding of acid-base reactions is crucial across multiple fields including biology, environmental science, and medicine. Recognizing these interactions helps explain phenomena like buffer solutions, whose role is to maintain a stable pH in biological systems.