Qualitative reactions to organic substances, anions, cations

Qualitative reactions to organic substances, ions and cations allow to determine the presence of various compounds by means of accessible, in most cases simple methods. They can be carried out with the help of indicators, hydroxides, oxides. Science, which studies the properties and structure of various substances, is called "chemistry". Qualitative reactions are part of the practical section of this science.

Classification of inorganic substances

All substances are divided into organic and inorganic. To the first belong classes of compounds such as salts, hydroxides (bases, acids and amphoteric) and oxides, also simple compounds (CI2, I2, H2 and others consisting of one element).

Salts consist of a cation of a metal, as well as an anion of an acid residue. The composition of acid molecules includes cations H + and anions of acid residues. Hydroxides consist of metal and anion cations in the form of hydroxyl group OH-. The composition of the oxide molecules includes atoms of two chemical elements, one of them is necessarily oxygen. They can be acidic, basic and amphoteric. As their name implies, they are able to form different classes of substances in the course of certain reactions. Thus, acidic oxides react with water to form acids, and basic acids form bases. Amphoteric, depending on the conditions, can exhibit the properties of both types of oxides. These include compounds of iron, beryllium, aluminum, tin, chromium, lead. Their hydroxides are also amphoteric. To determine the presence in the solution of various inorganic substances, qualitative reactions to ions are used.

A variety of organic substances

This group includes chemical compounds, whose molecules necessarily include carbon and hydrogen. They can also contain oxygen atoms, nitrogen, sulfur and many other elements.

They are subdivided into such basic classes: alkanes, alkenes, alkynes, organic acids (nucleic, fatty, saturated, amino acids and others), aldehydes, proteins, fats, carbohydrates. Many qualitative reactions to organic substances are carried out using a variety of hydroxides. Also, reagents such as potassium permanganate, acids, oxides can be used for this.

Qualitative reactions to organic substances

The presence of alkanes is mainly determined by the elimination method. If you add potassium permanganate, it does not discolor. These substances burn with a light-blue flame. Alkenes can be detected by adding bromine water or potassium permanganate. Both these substances, when interacting with them, become discolored. The presence of phenol can also be determined by adding a solution of bromine. At the same time, it will discolor and precipitate. In addition, the presence of this substance can be detected using a solution of ferric chloride, which when interacted with it will give a violet-brown color. Qualitative reactions to organic substances of the class of alcohols consist in the addition of sodium. In this case, hydrogen will be released. Burning of alcohols is accompanied by a light blue flame.

Glycerin can be detected with the help of cuprum hydroxide. In this case, glycerates are formed, which give the solution a cornflower color. Determine the presence of aldehydes can be done with the help of argentum oxide. As a result of this reaction, a pure argentum is released, which precipitates.

There is also a qualitative reaction to aldehydes, which is carried out with the help of copper hydroxide. To conduct it it is necessary to heat the solution. At the same time, he must change the coloring first from blue to yellow, then to red. Proteins can be detected using nitrate acid. As a result, a yellow precipitate is formed. If you add hydroxide kupruma, it will be purple. Qualitative reactions to organic substances of the class of acids are carried out with the help of litmus or ferric chloride. In both cases, the solution changes color to red. If sodium carbonate is added, carbon dioxide will be released.

Qualitative reactions to cations

With their help, it is possible to determine the presence of any metals in the solution of ions. Qualitative reactions to acids consist in the identification of the cation H +, which is included in their composition. This can be done in two ways: with litmus or methylorange. The first in the acid medium changes its coloration to red, the second - to pink.

Lithium, sodium and potassium cations can be distinguished by their flame. The first burn in red, the second with yellow, and the third with a purple flame. Calcium ions are detected by the method of adding carbonate solutions, resulting in a white precipitate.

Qualitative reactions to anions

The most common of these is the detection of OH-, so you can find out whether the base is present in the solution. This requires indicators. This phenolphthalein, methylorange, litmus. The first in such an environment acquires a crimson color, the second - yellow, the third - blue.