# Solubility and concentration relationship

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Considering the relation between solubility and \(K_{sq}\) is Recall that the definition of solubility is the maximum possible concentration of a. The extent of the solubility of a substance in a specific solvent is measured as the saturation concentration, where adding more solute does not. Define concentration, and explain how to calculate it. Solubility is the amount of solute that can dissolve in a given amount of solvent at a.

Likewise, if the pressure of the gas in the system decreases, gas becomes less soluble in the solvent.

Only applies if the gas molecules are in equilibrium Does not apply if there is a chemical reaction between the solvent and the solute. For example, if pressure is applied to a system, the dissolution reaction will respond to minimize this stress by reducing the pressure in the system.

Heat of solution Solids and liquids are a result of individual particles held together by winter particulate bonds.

Heat energy is also required to break the bonds in a solvent to insert one of the molecules into solution. Hence these processes are endothermic.

Heat energy is released when the solute molecules form bonds with the solvent molecules i. Depending on whether more energy is used to break the bonds within the solute and solvent or is released when new bonds are formed between the solute and solvent, the reaction overall can be exothermic or endothermic.

If more energy is required to break the bonds within the solute and solvent than the energy released when new bonds are formed between the solute and solvent, then the reaction is endothermic. If more energy is released when new bonds are formed between the solute and solvent than the energy required to break the bonds within the solute and solvent, then the reaction is exothermic.

When scuba divers submerge themselves in deep water, the pressure in their body increases.

This causes the nitrogen in their body to dissolve in their blood. Nitrogen is physiologically inert, so it is not used in tissue metabolism.

If the scuba diver ascends to the surface too quickly, the sudden drop in pressure causes nitrogen bubbles to come out of solution and form painful and potentially fatal gas embolisms.

Clinical Significance Dissolution Dissolution is important for health practitioners because, for drugs to be absorbed and have a physiological effect in the human body, they must be in solution. For solid preparations, such as tablets and suppositories, the rate of dissolution affects how fast a drug is absorbed in the body. Solubility Aqueous solubility is often considered when formulating drugs.

Poorly soluble formulations provide difficulties in the development of pharmaceuticals. Chloramphenicol, phenytoin, and digoxin are some examples. Drugs, particularly those for oral administration, which have low aqueous solubility may have low bioavailability leading to insufficient exposure in the body causing the drug to be not as effective.

## How does concentration affect solubility?

Questions To access free multiple choice questions on this topic, click here. Temperature and solvent effects in the solubility of some pharmaceutical compounds: Eur J Pharm Sci. Crystal engineering of active pharmaceutical ingredients to improve solubility and dissolution rates. Leuner C, Dressman J. It is also possible to predict solubility from other physical constants such as the enthalpy of fusion. The partition coefficient Log P is a measure of differential solubility of a compound in a hydrophobic solvent 1-octanol and a hydrophilic solvent water.

The logarithm of these two values enables compounds to be ranked in terms of hydrophilicity or hydrophobicity. The energy change associated with dissolving is usually given per mole of solute as the enthalpy of solution. Applications Solubility is of fundamental importance in a large number of scientific disciplines and practical applications, ranging from ore processing and nuclear reprocessing to the use of medicines, and the transport of pollutants.

Solubility is often said to be one of the "characteristic properties of a substance", which means that solubility is commonly used to describe the substance, to indicate a substance's polarity, to help to distinguish it from other substances, and as a guide to applications of the substance.

• 17.2: Relationship Between Solubility and Ksp
• Solubility

For example, indigo is described as "insoluble in water, alcohol, or ether but soluble in chloroform, nitrobenzene, or concentrated sulfuric acid". For example, a mixture of salt sodium chloride and silica may be separated by dissolving the salt in water, and filtering off the undissolved silica.

The synthesis of chemical compounds, by the milligram in a laboratory, or by the ton in industry, both make use of the relative solubilities of the desired product, as well as unreacted starting materials, byproducts, and side products to achieve separation.

Another example of this is the synthesis of benzoic acid from phenylmagnesium bromide and dry ice. Benzoic acid is more soluble in an organic solvent such as dichloromethane or diethyl etherand when shaken with this organic solvent in a separatory funnelwill preferentially dissolve in the organic layer. The other reaction products, including the magnesium bromide, will remain in the aqueous layer, clearly showing that separation based on solubility is achieved.

This process, known as liquid—liquid extractionis an important technique in synthetic chemistry. Recycling is used to ensure maximum extraction. Differential solubility In flowing systems, differences in solubility often determine the dissolution-precipitation driven transport of species. This happens when different parts of the system experience different conditions.

### Relationship Between Solubility and Ksp - Chemistry LibreTexts

Even slightly different conditions can result in significant effects, given sufficient time. For example, relatively low solubility compounds are found to be soluble in more extreme environments, resulting in geochemical and geological effects of the activity of hydrothermal fluids in the Earth's crust. These are often the source of high quality economic mineral deposits and precious or semi-precious gems. In the same way, compounds with low solubility will dissolve over extended time geological timeresulting in significant effects such as extensive cave systems or Karstic land surfaces.

Solubility of ionic compounds in water Main articles: Solubility chart and Solubility table Some ionic compounds salts dissolve in water, which arises because of the attraction between positive and negative charges see: