Solubility

A measure of the maximum amount of a solute that can be dissolved in a solvent

Solubility is the ability of a solute to dissolve in a solvent. The solubility of a substance in another is not unlimited, and how much solute you can solve in a solvent varies a lot.  Tabulated values of solubility refer to max grams of solute in a given amount of the solvent.

• solubility is dependent on temperature. In general, but not without expectations, solubility increases with temperature
• smaller particles dissolves faster than larger particles
• a solid dissolves faster if the mixture is stirred or shaken

A saturated solution contains the maximum amount of solute in the solvent, given by the solubility.

Examples of common solutions:

• tea with sugar - a solution of sugar in hot water (tea)
• seawater - a solution of salt in water

See more at Solutions, molarity and dilution

Example 1

Sodium chloride, NaCl, is the salt used for cooking. This salt has a solubility of 36 g in 100 g of water at 25°C.

What is the concentration (in wt%) of a saturated NaCl water solution at 25°C?

A saturated solution contains the maximum amount of solute in the solvent, which for NaCl is 36 grams in water at 25°C. Then, the concentration of the saturated solution is:  g NaCl /g NaCl solution *100%

NaCl concentration = 36 [g]/(100 + 36)[g] * 100% = 26.5 wt%

Example 2

What will be the concentration (in wt%) if you add 34 g NaCl to 100 g of water?

34 g NaCl is less than the solubility, which means that all the salt will be solved in water at 25°C.

NaCl concentration = 34 [g]/(100+34) [g] * 100% = 25.4 wt%

Example 3

What will be the concentration (in wt%) of the salt solution if you add 38 g NaCl to 100 g of water?

38 g NaCl is more than the solubility of NaCl in water. This means that the solution will be saturated and some of the salt will remain undissolved at 25°C. The concentration of the saturated solution is the same as in Example 1:

NaCl concentration = 36 [g]/(100 + 36)[g] * 100% = 26.5 wt%

Related Topics

• Fluid Mechanics - The study of fluids - liquids and gases. Involves velocity, pressure, density and temperature as functions of space and time
• Basics - The SI-system, unit converters, physical constants, drawing scales and more

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