What is the conjugate acid of each of the following?
1. NH₃
2. Cl⁻
3. HO⁻
4. H₂O

Verified step by step guidance

1. Step 1: Understand the concept of a conjugate acid. A conjugate acid is formed when a base gains a proton (H⁺). This involves identifying the base and adding an H⁺ to it.
2. Step 2: For NH₃ (ammonia), add an H⁺ to the molecule. This results in NH₄⁺ (ammonium ion). Write the chemical equation: NH₃ + H⁺ → NH₄⁺.
3. Step 3: For Cl⁻ (chloride ion), add an H⁺ to the ion. This results in HCl (hydrogen chloride). Write the chemical equation: Cl⁻ + H⁺ → HCl.
4. Step 4: For HO⁻ (hydroxide ion), add an H⁺ to the ion. This results in H₂O (water). Write the chemical equation: HO⁻ + H⁺ → H₂O.
5. Step 5: For H₂O (water), add an H⁺ to the molecule. This results in H₃O⁺ (hydronium ion). Write the chemical equation: H₂O + H⁺ → H₃O⁺.

Key Concepts

Conjugate Acid-Base Theory

In acid-base chemistry, a conjugate acid is formed when a base accepts a proton (H+). This theory, primarily based on the Brønsted-Lowry definition, emphasizes the transfer of protons between species. Understanding this concept is crucial for identifying the conjugate acids of various bases, as it allows for the prediction of their behavior in chemical reactions.

Ammonia (NH3) as a Base

Ammonia (NH3) is a common weak base that can accept a proton to form its conjugate acid, ammonium (NH4+). This reaction illustrates the basic nature of ammonia, which is often involved in acid-base reactions. Recognizing ammonia's role as a base is essential for determining its conjugate acid.

Water (H2O) as an Amphoteric Substance

Water (H2O) is an amphoteric substance, meaning it can act as both an acid and a base. When it acts as a base, it can accept a proton to form the hydronium ion (H3O+), which is its conjugate acid. This dual behavior is important for understanding the conjugate acids of other species, such as hydroxide (HO−) and chloride (Cl−), in aqueous solutions.