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6.2: Solubility- Ionic Compounds

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    Learning Objectives
    • Know how to use solubility rules.

    The only common liquid that can dissolve ionic compounds to any significant extent is water.

    Not all ionic compounds dissolve in water, but when they do, they disassociate or "break up" into their ions as shown in figure 1 below.

    The diagram shows eight purple sphe
    Figure \(\PageIndex{1}\): As potassium chloride (KCl) dissolves in water, the ions are hydrated. The polar water molecules are attracted by the charges on the K+ and Cl− ions. Water molecules in front of and behind the ions are not shown.

    Solubility Rules

    Although some ionic compounds will dissolve easily in water, others will not to any significant extent. To get a rough idea of whether an ionic compound will dissolve, use the table below. Generally, look up the anion of the ionic compound in the list on the left, then look to the right to see if it is combined with a cation that makes it an exception to the general rule.

    Table \(\PageIndex{1}\): Solubility Rules for Soluble Substances
    clipboard_e40d413ffee4b1c379ed6bd84bcd55f3b.png
    Example \(\PageIndex{1}\): Solubility

    Classify each compound as soluble or insoluble

    1. Zn(NO3)2
    2. PbBr2
    3. Sr3(PO4)2

    Solution

    1. All nitrates are soluble in water, so Zn(NO3)2 is soluble.
    2. All bromides are soluble in water, except those combined with Pb2+, so PbBr2 is insoluble.
    3. All phosphates are insoluble, so Sr3(PO4)2 is insoluble.
    Exercise \(\PageIndex{1}\): Solubility

    Classify each compound as soluble or insoluble.

    1. Mg(OH)2
    2. KBr
    3. Pb(NO3)2
    Answer a
    insoluble
    Answer b
    soluble
    Answer c
    soluble

    Summary

    Some ionic compounds dissolve in water. To determine if an ionic compound is soluble, look it up on a solubility table.

    Contributions & Attributions

    This page was constructed from content via the following contributor(s) and edited (topically or extensively) by the LibreTexts development team to meet platform style, presentation, and quality:

    This page titled 6.2: Solubility- Ionic Compounds was last modified on Tue, 16 Dec 2025 03:18:15 GMT and is shared under a not declared license and was authored, remixed, and/or curated by Seth Yates.

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