---
title: "Weak Base — AP Chem Definition, Kb & Buffer Connection"
description: "A weak base only partially ionizes in water, reaching equilibrium described by Kb. It anchors AP Chem Unit 8 buffers, pOH math, and Henderson-Hasselbalch."
canonical: "https://fiveable.me/ap-chem/key-terms/weak-base"
type: "key-term"
subject: "AP Chemistry"
---

# Weak Base — AP Chem Definition, Kb & Buffer Connection

## Definition

A weak base is one that does not completely dissociate into its ions in water.

## Related Study Guides

- [8.9 Henderson-Hasselbalch Equation](/ap-chem/unit-8/henderson-hasselbalch-equation/study-guide/9jNGg5JlJAYF5QilwfJW)
- [8.8 Properties of Buffers](/ap-chem/unit-8/properties-buffers/study-guide/PlRbvlggdbKMOXSUWfmD)
- [8.1 Introduction to Acids and Bases](/ap-chem/unit-8/intro-acids-bases/study-guide/rG2ZBgD9evdBohz4a7Mj)

## Review

### Related Terms

- Base Dissociation Constant (Kb): The equilibrium constant for the reaction of a base with water to form conjugate acid and hydroxide ion.
- [pOH](/ap-chem/key-terms/poh): It measures the basicity or alkalinity of an aqueous solution on a logarithmic scale.
- Hydroxide Ion (OH-): The negative ion formed by one oxygen bonded to one hydrogen; it can be found in many bases.