Problem 48 - Chemistry: An Atoms-Focused Approach

Question

What is the difference between a strong base and a weak base?

Step-by-Step Solution

Answer

Answer: A strong base is a base that completely ionizes in an aqueous solution, producing hydroxide (OH⁻) ions, while a weak base only partially ionizes. Examples of strong bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH), and examples of weak bases are ammonia (NH₃) and methylamine (CH₃NH₂). In a solution, strong bases fully dissociate and release more hydroxide ions, resulting in a higher pH, whereas weak bases partially dissociate and release fewer hydroxide ions, leading to a lower pH.

Step 1: Define strong and weak bases

A strong base is a base that completely ionizes (dissociates) in an aqueous solution, producing hydroxide (OH⁻) ions. Typically, these are metal hydroxides. A weak base, on the other hand, is a base that only partially ionizes in an aqueous solution, producing hydroxide ions in a partial or limited manner.

Step 2: Provide examples of strong and weak bases

Examples of strong bases include sodium hydroxide (NaOH) and potassium hydroxide (KOH), while examples of weak bases are ammonia (NH₃) and methylamine (CH₃NH₂).

Step 3: Discuss the behavior of strong and weak bases in solutions

In a solution, a strong base will fully dissociate and release hydroxide ions, leading to a higher concentration of OH⁻ ions and therefore a higher pH. Conversely, a weak base will only partially dissociate, releasing fewer hydroxide ions, resulting in a lower concentration of OH⁻ and a lower pH.

Step 4: Describe the effect of concentration on the strength of a base

The strength of a base in a solution depends not only on its inherent properties, but also on its concentration. A weak base in a higher concentration can be more basic (have a higher pH) than a strong base in a lower concentration. For example, a stronger concentration of ammonia (a weak base) could have a higher pH than a dilute solution of sodium hydroxide (a strong base).

Step 5: Compare strong and weak bases in chemical reactions

In chemical reactions, strong bases tend to react more readily and completely with acids, neutralizing them and forming a salt and water as products. Weak bases, on the other hand, will react less readily and may not completely neutralize an acid, leaving some of the weak base as an unreacted species in the final solution.