in chemistry, solution It is a homogeneous mixture of two or more pure substances that cannot be isolated from each other, such as filtration, for example. It consists of a solvent and a solute, and often the solvent is greater than the solute, such as a solution of sugar in water.^[1][2][3] The process of decomposition or disintegration is also called dissolution. They can be separated by evaporation, for example, so that it does not cause any chemical reaction between the two substances, for example, a solution of table salt in water.

Types of solutions[عدل]

There are three main types of solutions:

liquid solution[عدل]

It results from the dissolution of a solid in another liquid, and also results from the dissolution of something solid or gaseous in a liquid. Examples: the dissolution of salt in water, and the dissolution of sugar in tea.

gaseous solution[عدل]

It is the solution that arises by dissolving the solid, liquid, or gaseous substance in the liquid substance, and results from the mixing of gases. Air, for example, is a gaseous solution, consisting of a mixture of nitrogen and oxygen, with trace amounts of argon and carbon dioxide.

bullion[عدل]

Metal molten solutions are called alloys. The alloy usually consists of several metals and non-metals, such as some types of molten steel, as it consists of chromium, vanadium and carbon dissolved in iron.

Methods for expressing the concentration of a solution[عدل]

• Molarity is defined as the dissolution of 1 mole of a substance in 1 liter of water.

or:

Molarity (M) = number of moles of solute ÷ volume of solution in liters

or:

Molality (M) = weight of the solute / (molecular weight of the substance * volume of solution in liters)

Example:

For a compound such as sodium chloride: the atomic weight of chlorine is (4.35 grams) and the atomic weight of sodium is (23 grams). Given that the composition of the molecule is NaCl (i.e. 1 sodium combined with 1 chlorine), 1 mole of sodium chloride is 4.58 grams.

That is, if we dissolve 4 and 58 grams of table salt in 1 liter of water, we have a solution of 1 molarity.

• When we dissolve 29.2 grams of sodium chloride in 1/2 liter of water, we have a solution with a molarity of 1.
• When we dissolve 14.6 grams of sodium chloride in 1/4 liter of water, we also have a 1 molarity solution.

Other definitions of solutions:

Chemists use solutions with other designations, such as normalite:

• Normality N = molarity / valency of the substance

The normality of a substance is defined as the number of moles of a substance dissolved in 1 liter of water divided by the valency of the substance.

• molecular fracture
• percentage

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Liquid solutions are classified according to the state of the dissolved particles as follows:

• real solutions: It is the one in which the solute particles are not filtered and are not separated by filtration. The dissolved particles cannot be distinguished with the naked eye or with a microscope – its components cannot be separated by decantation or filtration – Homogeneous – like sugar in water
• Colloidal solutions: It is in which the solute particles are not completely dissolved in the solvent and can be seen clearly in the solution. The solute particles can be distinguished by electron microscopy – its components cannot be separated by decantation or filtration – homogeneous – like milk in blood
• Suspended solutions: It is the one in which solute particles are deposited, such as: water and sand. The particles of the solute can be distinguished by eye – its components can be separated by decantation or filtration – it is not homogeneous – like chalk in water

• Emulsions: Emulsions are a viscous liquid pharmaceutical form with a milky appearance, intended for internal or oral use. It consists of two phases, one of which is distributed inside the other to form an emulsion. By using an emulsifying agent, the liquid suspended in the form of droplets is called the dispersed phase or the internal phase, while the liquid in which the fine droplets are dispersed is called the continuous phase, the dispersing phase, or the external phase.
  • Advantages of emulsions 1. The fractionation of medicinal substances into small droplets increases the rate of their absorption in the intestine. 2. Masking the unacceptable taste and smell of the oil, as in castor oil emulsions. 3. Prolong the effect of the drug and increase its aromatic effect, according to its formulation. 4. Water is a cheap excipient and has a high ability to dissolve pharmaceutical substances.
  • Types of emulsions Emulsions are classified according to the contents of their liquid phases into two types: 1. Emulsions of oil in water (g/m) where the outer phase is water and the inner phase is oil and the like is milk. Hydrophilic emulsifiers and super-gum are used to prepare such type. 2. Water-in-oil emulsions (m/g) where the outer phase is oil and the inner phase is water and an example of that is butter. To prepare this type, oil-loving emulsifiers such as Wool Fat, Beezwax and others are used.
  • Examples of emulsions 1. Castor oil emulsion, which is used as an intense laxative, at a dose of 50-100 ml, and in radiography of the gastrointestinal tract, at a rate of 120 ml at once. 2. An emulsion of paraffin oil, which is used as a laxative and laxative, in the amount of 30 ml. 3. Cod liver oil emulsion, which is used as a source of vitamin A and vitamin D, in an amount of 15 ml.

saturation[عدل]

It is also classified according to the percentage of solute particles concentration in the solvent, as follows:

• Saturated solutions:

The amount of a substance that can dissolve in a solvent depends on its solubility in that solvent. If we dissolve the largest possible amount of solute in a solvent, the solution becomes a saturated solution. That is, if we add some of the dissolved substance to such a solution, it will precipitate and not dissolve.

• unsaturated solutions:

A solution that contains less solute than the amount that brings it to saturation.

• supersaturated solutions:

A saturated solution has this characteristic at a certain temperature, and its saturation depends on the temperature, that is, if we raise the temperature of a saturated solution by two degrees Celsius, it will dissolve a larger amount of the solute at that high temperature. If we assume that we have a solution saturated with table salt at a temperature of 82 degrees Celsius, then if we suddenly lower the temperature to 81 degrees Celsius, for example, the solution becomes “super saturated” for a short time, and then the excess salt precipitates.

Separation of solutions[عدل]

The solute can be separated from the solvent as no chemical reaction occurs in the solution.

When salt is dissolved in a solution, the bonds of the ions forming the salt crystals are broken, and water molecules accumulate around the ions in what is called “hydration”. And the ions of some metals with water molecules form complex cations (such as iron (III) hexahydrate). In order for these mixtures to be considered solutions, these bonds must be completely inverse.

Also, when hydrides of acids and bases are dissolved, chemical reactions occur. Hydrogen chloride dissolves in water and dissociates immediately into chlorine ions and hydrogen ions, and hydrogen ions react with water forming oxonium ions.

Carbon dioxide remains almost in the gaseous state in a solution of it in water. But part of it with water is carbonic acid, and this dissolves in water and forms hydrogen carbonate, carbonate, and oxonium. These reactions are reversible reactions, that is, the materials of the solution can be separated without adding other reaction materials.

Separation of solids from a liquid[عدل]

The process of evaporating a solution works to saturate the solid in the solution and crystallize it as long as the solubility of the substance in the liquid is limited. When evaporation is complete, the solid remains at the bottom of the evaporation container.

Some solutions of a solid such as calcium carbonate decompose during the evaporation of a concentrated solution of it and do not remain unchanged after the evaporation is complete but are transformed into calcium carbonate and precipitate while carbon dioxide evaporates with water.

A method that is used a lot in practical application, which is reverse osmosis. In it, the solution is pressed through a semi-permeable membrane, and the membrane traps ions and large molecules, and the liquid (water) passes through it. This technology is applied in water processing, especially in water desalination.

Crop mixed soil[عدل]

Follow the method of distillation or the method of fractional distillation to separate mixtures of liquids. In these two cases, we take advantage of the difference in the boiling point of the liquids that make up the solution. Since the liquid with a high boiling point also has a little vapor pressure, part of it moves with the vapor of the liquid with a low boiling point and condenses with it in the receiving flask. Therefore, by distilling alcohol, we obtain a purity of 96% only. If we want to obtain alcohol of higher purity, then the distillation process must be carried out a second time on the alcohol gained from the first distillation process.

Distillation is widely used technically in petroleum refining, where we isolate from oil: kerosene, diesel, naphtha, tar and other petroleum products, due to the different boiling points of each of them.

the glass[عدل]

Glass is also considered a solution, as it consists of a mixture of cold liquids. The glass is distinguished by the fact that the atoms in it are irregular in a crystalline network. They are distributed randomly in the solid glass, but they lose their distinctive movement when the glass is in the liquid state.

special cases[عدل]

The “dissolution” of a metal in an acid is not a solubility, but rather a chemical reaction.

However, there are special cases in which a reversible chemical reaction and melting occur at the same time, such as:

• The dissolution of sodium in ammonia.
• The dissolution of carbon dioxide in water, where an equilibrium occurs with the formation of carbonic acid and its loose particles (bicarbonate ions and carbonate ions) that disappear when carbon dioxide leaves the solution (such as being expelled from the solution by another gas).

See also[عدل]

• electrolyte
• retail distillery
• Concentration
• mall
• Phase diagram
• solid solution

Reference[عدل]

On Commons, photos and files for: solution

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