Question

Differentiate between the terms strength and concentration as they apply to acids and bases. When is HCl strong? Weak? Concentrated? Dilute? Answer the same questions for ammonia. Is the conjugate base of a weak acid a strong base?

Short answer

The strength of an acid or base refers to its ability to dissociate in water, while concentration describes the amount of acid or base in a solution. HCl is a strong acid and can be concentrated or dilute depending on the moles per liter. Ammonia is a weak base and also can be concentrated or dilute. Generally, the conjugate base of a weak acid is a strong base, as it has a high tendency to react with water and form hydroxide ions, though there are exceptions.

Step-by-step solution

Definition of strength

The strength of an acid or base refers to its ability to dissociate in water, forming ions. A strong acid or base is one that almost completely dissociates into its constituent ions, while a weak acid or base does not dissociate completely, and a significant amount of the molecule remains in its original form.

Definition of concentration

Concentration, on the other hand, describes the amount of an acid or base dissolved in a solution. It is typically expressed in moles per liter (M). A concentrated acid or base has a high amount of the substance in the solution, while a dilute acid or base has a lower amount. #Step 2: Describe properties of HCl#

HCl strength

Hydrochloric acid (HCl) is a strong acid. This means that it almost completely dissociates in water forming hydrogen ions (H+) and chloride ions (Cl-).

HCl concentration

HCl can be concentrated or diluted depending on the amount of HCl dissolved in water. For example, a 12 M HCl solution is considered concentrated, while a 0.1 M solution is considered diluted. #Step 3: Describe properties of ammonia#

Ammonia strength

Ammonia (NH3) is a weak base. In water, it reacts partially with water molecules to produce hydroxide ions (OH-) and ammonium ions (NH4+), but a significant amount of ammonia molecules remain undissociated in the solution.

Ammonia concentration

Like HCl, ammonia can be concentrated or diluted depending on the amount of NH3 dissolved in water. For example, a 14.8 M ammonia solution is considered concentrated, and a 0.01 M solution is considered diluted. #Step 4: Conjugate base of a weak acid#

Relationship between weak acid and its conjugate base

The conjugate base of a weak acid is generally a strong base. This is because a weak acid does not dissociate completely in water, leaving a lot of its conjugate base undissociated. In order for an equilibrium to be established, the conjugate base must have a strong tendency to react with water and form hydroxide ions (OH-). However, this is not universally true as there are exceptions where the conjugate base of a weak acid is also weak.