pKa Calculator

Table of Contents

• Introduction
• Understanding pKa
• Formula
• Examples
• Reference Tables
• FAQs

Introduction

The pKa Calculator is designed to make acid-base calculations simple and accurate. With a clean interface, users can either enter their own values or select common acids and bases.

This tool is essential for students, chemists, and researchers working in labs. Understanding the strength of acids and bases is critical for predicting reaction behavior.

By providing real-time calculations, the calculator ensures quick feedback. Users can instantly see how pH and concentrations affect the pKa value.

Understanding pKa

The pKa of a substance represents the acid dissociation constant on a logarithmic scale. It measures how easily an acid donates a proton to a base.

Lower pKa values indicate strong acids that dissociate easily. Higher pKa values correspond to weaker acids that hold onto their protons.

Using this calculator, you can quickly compare different acids and determine their relative strengths. It is particularly useful in titration experiments and buffer preparation.

• Instant calculation of pKa from pH and concentration values
• Supports both common acids and custom entries
• Real-time result updates for faster experimentation

Formula

The Henderson-Hasselbalch equation is the core of this calculation:

pKa = pH - log10([A⁻]/[HA])

Here, [A⁻] is the concentration of the conjugate base, and [HA] is the concentration of the acid. By entering these values, the calculator computes pKa instantly.

Examples

Here are some practical examples to help you understand pKa calculations:

• Example 1: pH = 4.76, [A⁻] = 0.1 M, [HA] = 0.2 M → pKa ≈ 4.47
• Example 2: pH = 7, [A⁻] = 0.05 M, [HA] = 0.05 M → pKa = 7
• Example 3: pH = 3.75, [A⁻] = 0.01 M, [HA] = 0.1 M → pKa ≈ 2.75
• Example 4: pH = 9.25, [A⁻] = 0.2 M, [HA] = 0.05 M → pKa ≈ 10.81
• Example 5: pH = 2.15, [A⁻] = 0.01 M, [HA] = 0.1 M → pKa ≈ 1.15

Reference Tables

This table provides a quick reference for commonly used acids and their pKa values. It helps to quickly identify acid strength and plan experiments.

Understanding the pKa of conjugate acids allows for predicting reaction equilibria. It helps in buffer design and predicting the ionization of bases in solution.

Frequently Asked Questions