<P> All solutions have a positive entropy of mixing . The interactions between different molecules or ions may be energetically favored or not . If interactions are unfavorable, then the free energy decreases with increasing solute concentration . At some point the energy loss outweighs the entropy gain, and no more solute particles can be dissolved; the solution is said to be saturated . However, the point at which a solution can become saturated can change significantly with different environmental factors, such as temperature, pressure, and contamination . For some solute - solvent combinations a supersaturated solution can be prepared by raising the solubility (for example by increasing the temperature) to dissolve more solute, and then lowering it (for example by cooling). </P> <P> Usually, the greater the temperature of the solvent, the more of a given solid solute it can dissolve . However, most gases and some compounds exhibit solubilities that decrease with increased temperature . Such behavior is a result of an exothermic enthalpy of solution . Some surfactants exhibit this behaviour . The solubility of liquids in liquids is generally less temperature - sensitive than that of solids or gases . </P> <P> The physical properties of compounds such as melting point and boiling point change when other compounds are added . Together they are called colligative properties . There are several ways to quantify the amount of one compound dissolved in the other compounds collectively called concentration . Examples include molarity, volume fraction, and mole fraction . </P> <P> The properties of ideal solutions can be calculated by the linear combination of the properties of its components . If both solute and solvent exist in equal quantities (such as in a 50% ethanol, 50% water solution), the concepts of "solute" and "solvent" become less relevant, but the substance that is more often used as a solvent is normally designated as the solvent (in this example, water). </P>

Solution of plant or chemical dissolved in alcohol