Common-ion effect

<p>In <a href="/facts/Chemistry/SrNqkGVm">chemistry</a>, the common-ion effect refers to the decrease in <a href="/facts/Solubility/kLE9h3Jb">solubility</a> of an ionic <a href="/facts/Precipitation_(chemistry)/s3BgsLLY">precipitate</a> by the addition to the <a href="/facts/Solution_(chemistry)/MGchhMQV">solution</a> of a soluble compound with an <a href="/facts/Ion/3bePpDna">ion</a> in common with the precipitate. This behaviour is a consequence of <a href="/facts/Le_Chatelier%27s_principle/sHkpGM0r">Le Chatelier's principle</a> for the <a href="/facts/Equilibrium_reaction/y8ToYXHp">equilibrium reaction</a> of the <a href="/facts/Ion_association/dacS8wXj">ionic association</a>/<a href="/facts/Dissociation_(chemistry)/gDRGdeSN">dissociation</a>. The effect is commonly seen as an effect on the solubility of <a href="/facts/Salt_(chemistry)/lsSKwGpn">salts</a> and other <a href="/facts/Weak_electrolyte/4YE8bIVa">weak electrolytes</a>. Adding an additional amount of one of the ions of the salt generally leads to increased precipitation of the salt, which reduces the <a href="/facts/Concentration/wqBmz5od">concentration</a> of both ions of the salt until the <a href="/facts/Solubility_equilibrium/MNBoGyJb">solubility equilibrium</a> is reached. The effect is based on the fact that both the original salt and the other added chemical have one ion in common with each other.
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Common-ion effect open-in-new

Common-ion effect