Question

What is the difference between a week and strong base

Answer 1

I assume you mean "weak base" vs "strong base." Key differences:

Definition
- Strong base: essentially completely dissociates/ionizes in water to give OH−. Example: NaOH, KOH, Ba(OH)2.
- Weak base: only partially ionizes in water; an equilibrium exists between base, water, and OH−. Example: NH3, CH3NH2, pyridine.

How it's expressed
- Strong base: no useful equilibrium constant for ionization because dissociation is essentially 100% for typical concentrations.
- Weak base: characterized by a base dissociation constant Kb (or by pKb). Larger Kb = stronger weak base.

Typical consequences
- OH− concentration: a strong base at a given molarity produces much more OH− than a weak base at the same molarity.
- pH: strong-base solutions are more basic (higher pH) than equal-concentration weak-base solutions.
- Conductivity: strong-base solutions conduct electricity better because they provide more free ions.
- Titration: titration of a strong base with a strong acid has an equivalence point at pH ≈ 7; titration of a weak base with strong acid has an equivalence point at pH < 7.
- Conjugate acids: a strong base has a very weak conjugate acid; a weak base has a relatively stronger conjugate acid.

Examples (numeric)
- 0.10 M NaOH (strong): [OH−] ≈ 0.10 M → pOH = 1 → pH ≈ 13.
- 0.10 M NH3 (Kb ≈ 1.8×10−5): [OH−] ≈ sqrt(Kb·C) ≈ 1.3×10−3 M → pOH ≈ 2.87 → pH ≈ 11.13.

Important caveat
- Strength is not the same as concentration. A concentrated weak base can have higher pH than a very dilute strong base.

Why a base is weak or strong (factors)
- Availability of the lone pair (electronegativity, resonance, hybridization)
- Solvation/hydrogen-bonding in water and steric hindrance
- The stability of the conjugate acid

If you want, I can show more example calculations, compare titration curves, or list common strong and weak bases. Which would you like?