Aqueous Salt Solutions - Acid and Base Properties
Salts contains ions that may affect the pH in aqueous solutions in both acidic and basic directions.
It is possible to predict whether an aqueous solution of a salt with both basic and acidic properties will be basic, acidic or neutral by comparing the Ka value for the acidic ion with the Kb value for the basic ion.
See also Strong and weak acids and bases and Buffer solutions, as well as pKa of inorganic acids and bases, pKa of phenols, alcohols and carboxylic acids and pKa of amines, diamines and cyclic organic nitrogen compounds.
| Ka vs Kb | pH | Basic or acidic |
| Ka > Kb | < 7 | Acidic |
| Ka < Kb | > 7 | Basic |
| Ka = Kb | 7 | Neutral |
This table summarizes the acid-base properties of aqueous solutions of various salts:
For full table - rotate the screen!
| Type of salt | Examples | pH of solution | Comment | |
| Cation from | Anion from | |||
| Strong base | Strong acid | BaCl2, KCl, CaNO3, Na2SO4 | Neutral | Neither acts as an acid or a base |
| Strong base | Weak acid | NaF, KCHOO, NaHCO3 | Basic | Anion acts as a base Cation has no effect on pH |
| Conjugate acid of weak base | Strong acid | NH4Br, NH4NO3, | Acidic | Cation acts as an acid Anion has no effect on pH |
| Conjugate acid of weak base | Conjugate base of weak acid | NH4CN, NH4CH3COO | Acidic if Ka > Kb Basic if Kb > Ka Neutral if Ka = Kb | Cation acts as an acid Anion acts as a base |
| Highly charged metal ion | Strong acid | Al(NO3)3, CrCl3 | Acidic | Hydrated cations acts as an acid Anions has no effect on pH |
Related Topics
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Material Properties
Properties of gases, fluids and solids. Densities, specific heats, viscosities and more.
Related Documents
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Acid and Base pH Indicators
pH range vs. color change for acid and base indicators - together with pKa and structures of the indicators. -
Acids - pH Values
pH values of acids like sulfuric, acetic and more.. -
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Amines, Diamines and Cyclic Organic Nitrogen Compounds - pKa Values
Values for the negative logarithm of the acid dissociation constant, pKa, of the conjugated acid of amines, diamines and cyclic organic nitrogen compounds, shown together with the molecular structure of the acids. -
Bases - pH Values
pH values for bases like sodium hydroxide, ammonia and more. -
Buffer Solutions
Definitions, explanations and examples of how to make buffer solutions. -
Inorganic Acids and Bases - pKa Values
Values for the negative logarithm of the acid dissociation constant, pKa, of inorganic acids and bases, as well as hydrated metal ions. -
Phenols, Alcohols and Carboxylic Acids - pKa Values
For oxygen containing organic compounds this is given: pKa (the negative logarithm of the acid dissociation constant), molecular structures, molar weights, density and melting and boiling points. -
Strong and Weak Acids and Bases
The most common strong acids and bases, and some examples of weak acids and bases, together with definition of strong and weak acids and bases.
