Practically insoluble in water means a substance does not dissolve in water to a significant extent.
In more detail, when a substance is described as "practically insoluble" it implies that only a very, very small amount of the substance, if any, will dissolve in water, to the point where it is often considered negligible for most practical purposes. There isn't a universally agreed-upon quantitative definition for "practically insoluble" as it depends on the context and specific application. However, it generally refers to a solubility of less than 0.1 grams per 100 grams of water (or even less) at a specified temperature.
Here's a breakdown to understand this better:
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Solubility: This refers to the ability of a substance (the solute) to dissolve in a solvent (in this case, water).
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Insoluble: This implies that the solute does not dissolve in the solvent. However, "completely insoluble" is rare; most substances dissolve to some extent, no matter how small.
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Practically Insoluble: This acknowledges the reality that absolutely zero dissolution is unlikely. "Practically insoluble" means the amount that does dissolve is so minimal that, for all intents and purposes, we can treat it as if it doesn't dissolve.
Examples:
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Sand (Silicon Dioxide - SiO2): Sand is practically insoluble in water. You can put sand in water, and almost none of it will dissolve.
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Many Polymers: Certain polymers (plastics) are designed to be practically insoluble in water for applications like food packaging or water pipes.
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Silver Chloride (AgCl): While not completely insoluble, silver chloride's low solubility makes it practically insoluble for many applications.
Factors Affecting Solubility (Even in "Practically Insoluble" Substances):
Even for substances considered "practically insoluble," factors like:
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Temperature: Solubility often increases with temperature (although not always).
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Pressure: Pressure can affect the solubility of gases, but has a minimal effect on solids and liquids in water.
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pH: Changes in pH can sometimes influence the solubility of certain compounds.
In summary, "practically insoluble in water" is a term indicating that a substance dissolves in water to such a small extent that it's essentially considered not to dissolve for most practical uses.
