To understand how the hydrolysis of s alts in their aqueous solutions proceeds, we first give a definition of this process.
Definition and features of hydrolysis
This process involves the chemical action of water ions with s alt ions, as a result, a weak base (or acid) is formed, and the reaction of the medium changes. Any s alt can be represented as a chemical reaction product of a base and an acid. Depending on their strength, there are several options for the course of the process.
Types of hydrolysis
In chemistry, three types of reactions between s alt and water cations are considered. Each process is carried out with a change in the pH of the medium, so it is expected to use different types of indicators to determine the pH value. For example, purple litmus is used for an acidic reaction, phenolphthalein is suitable for an alkaline reaction. Let us analyze in more detail the features of each hydrolysis variant. Strong and weak bases can be determined from the solubility table, and the strength of acids can be determined from the table.
Cation hydrolysis
As an example of such a s alt, consider ferric chloride (2). Iron(2) hydroxide is a weak base, while hydrochloric acid is a strong base. In the process of interaction with water (hydrolysis), the formation of a basic s alt (iron hydroxochloride 2) occurs, and hydrochloric acid is also formed. An acidic environment appears in the solution, it can be determined using blue litmus (pH less than 7). In this case, the hydrolysis itself proceeds through the cation, since a weak base is used.
Let's give one more example of hydrolysis for the described case. Consider the magnesium chloride s alt. Magnesium hydroxide is a weak base, while hydrochloric acid is a strong base. In the process of interaction with water molecules, magnesium chloride turns into a basic s alt (hydroxochloride). Magnesium hydroxide, the general formula of which is M(OH)2, is sparingly soluble in water, but strong hydrochloric acid gives the solution an acidic environment.
Anion hydrolysis
The next hydrolysis option is typical for s alt, which is formed by a strong base (alkali) and a weak acid. As an example for this case, consider sodium carbonate.
This s alt contains a strong sodium base and a weak carbonic acid. Interaction with water molecules proceeds with the formation of an acidic s alt - sodium bicarbonate, that is, hydrolysis of the anion occurs. In addition, sodium hydroxide is formed in the solution, which makes the solution alkaline.
Let's give another example for this case. Potassium sulfite is a s alt that is formed by a strong base - caustic potassium, as well as a weaksulfuric acid. In the process of interaction with water (during hydrolysis), the formation of potassium hydrosulfite (acid s alt) and potassium hydroxide (alkali) occurs. The environment in the solution will be alkaline, you can confirm it with phenolphthalein.
Total hydrolysis
The s alt of a weak acid and a weak base undergoes complete hydrolysis. Let's try to find out what is its peculiarity, and what products will be formed as a result of this chemical reaction.
Let's analyze the hydrolysis of a weak base and a weak acid using aluminum sulfide as an example. This s alt is formed by aluminum hydroxide, which is a weak base, as well as a weak hydrosulphuric acid. When interacting with water, complete hydrolysis is observed, as a result of which gaseous hydrogen sulfide is formed, as well as aluminum hydroxide in the form of a precipitate. Such an interaction occurs both in the cation and in the anion, so this hydrolysis option is considered complete.
Also, magnesium sulfide can be cited as an example of the interaction of this type of s alt with water. This s alt contains magnesium hydroxide, its formula is Mg (OH) 2. It is a weak base, insoluble in water. In addition, there is hydrosulfide acid inside magnesium sulfide, which is weak. When interacting with water, complete hydrolysis occurs (according to the cation and anion), as a result of which magnesium hydroxide is formed in the form of a precipitate, and hydrogen sulfide is also released in the form of a gas.
If we consider the hydrolysis of s alt, which is formed by a strong acid and a strongbasis, it should be noted that it does not leak. The medium in solutions of s alts such as sodium chloride, potassium nitrate remains neutral.
Conclusion
Strong and weak bases, acids that form s alts, affect the result of hydrolysis, the reaction of the medium in the resulting solution. Similar processes are widespread in nature.
Hydrolysis is of particular importance in the chemical transformation of the earth's crust. It contains metal sulfides, which are sparingly soluble in water. As they hydrolyze, the formation of hydrogen sulfide occurs, its release in the process of volcanic activity to the surface of the earth.
Silicate rocks in the transition to hydroxides cause gradual destruction of rocks. For example, a mineral such as malachite is a product of the hydrolysis of copper carbonates.
Intensive process of hydrolysis also occurs in the oceans. Magnesium and calcium bicarbonates, which are carried out by water, have a slightly alkaline environment. Under such conditions, the process of photosynthesis in marine plants proceeds well, marine organisms develop more intensively.
In oil there are impurities of water and s alts of calcium and magnesium. In the process of heating oil, they interact with water vapor. During hydrolysis, hydrogen chloride is formed, the interaction of which with the metal causes the destruction of equipment.
