Aqueous Salt Solutions - Acid and Base Properties
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:
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| 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
• Material Properties
Properties of gases, fluids and solids. Densities, specific heats, viscosities and more.
Related Documents
Acid and Base pH Indicators
pH range vs. color change for acid and base indicators - together with pKa and structures of the indicators.
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pH values for bases like sodium hydroxide, ammonia and more.
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Definitions, explanations and examples of how to make buffer solutions.
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Values for the negative logarithm of the acid dissociation constant, pKa, of inorganic acids and bases, as well as hydrated metal ions.
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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.
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