What is salt?
class of chemical compounds which include a metal cation or ammonium cation, coupled with the anion of the acid residue is a common name - salt.They are divided into normal (or average), acidic, basic, double, hydrate (crystalline hydrates) complex.
For normal (or medium) salts characterized by the complete replacement of hydrogen cations at acid molecule on a metal cation or ammonium, eg Na2SO4 sodium sulfate or calcium carbonate CaCO3.If
acid molecule hydrogen cations partially substituted by a cation, such acid salts are called, for example, ammonium bicarbonate or sodium bicarbonate NH4HCO3 NaHCO3.
If the base molecule was not complete and partial substitution of hydroxyl groups on the acid radical, the salts formed are called basic, for example, copper digidroksokarbonat (CuOH) 2CO3.In formula
double salt contains two different cation, e.g., aluminum and potassium in potassium alum KAl (SO4) 2 • 12 H2O.In formula
mixed salt contains two different anion, e.g., bleach CaCl (OCl).
The structure of molecules of hydrated salts include water of crystallization such as copper sulfate (blue) CuSO4 • 5 H2O.
molecules consist of complex salts or complex cation complex anion, such as chloride tetraammintsinka (II) [(Zn (NH3) 4)] Cl2.
name as a way of salt?
salt is present in the names of two words.The first - the name of the anion, which is in the nominative case.The second word (in the genitive case) is derived from the name of the cation.For example, sodium sulphate Na2SO4, iron sulfate (II) FeSO4, iron sulfate (III) Fe2 (SO4) 3, CaCO3, calcium carbonate, copper chloride, CuCl2.The title acid salt anion is written before the name of the prefix "hydro" or the prefix "bi", if the molecule was one unsubstituted hydrogen cation.If there are two hydrogen cations left, before the name of the anion is written the prefix "dihydro".Examples: hydrogen (or hydrogen), sodium NaHCO3 (this salt is also the name of baking soda), sodium dihydrogen phosphate NaH2PO4.
Ammonium bicarbonate.Formula
The formula of the acid salt of carbonic acid NH4HCO3, wherein the cation is ammonium, is also the anion HCO3-, formed by partial substitution in the molecule of the acid hydrogen cation positively charged ammonium ion.That is, the molecule of the acid salt comprises a cation of ammonium, NH4 +, associated with one anion having a naming hydrogencarbonate HCO3-.Gross Hill formula system is written as: CH5NO3.The molecular weight of the substance and 79.06.e. m.
Properties
Ammonium bicarbonate is an inorganic compound, in appearance - a colorless crystals with rhombic lattice.Its density is 1.586 g / cm3 (20 ° C).The vapor pressure increases from 59 mm.Hg.Art.(at 25.4 ° C) to 278 mm.Hg.Art.(at 45 ° C).
Ammonium bicarbonate is not soluble in ethyl alcohol and acetone.It is readily soluble in water: with increasing temperature the solubility of the acid salt increases from 11.9 g / 100 g (0 ° C) to 36.6 g / 100 g (at 40 ° C).
Ammonium bicarbonate decomposes to CO2 emissions is already at 20 ° C.At a temperature of 36-70 ° C decomposes in aqueous salt solutions.As a result, ammonia is released, produced water and carbon dioxide: NH4HCO3 → NH3 + CO2 ↑ ↑ + H2O.
by hydrolysis of an aqueous solution of a weakly alkaline reaction.When adding a concentrated solution of ammonia formed normal salt: NH4HCO3 + NH3 → (NH4) 2CO3.
Under the action of acids and bases are destroyed by the acid salt reaction equations: NH4HCO3 + HCl → NH4Cl + CO2 ↑ + H2O or NH4HCO3 + 2 NaOH → Na2CO3 + NH3 • H2O + H2O.
Ammonium bicarbonate.Preparation
Like all hydrogencarbonates, acidic ammonium salt is obtainable by a long pass carbon dioxide through a solution of ammonium salts medium: (NH4) 2CO3 + H2O → CO2 + 2 NH4HCO3.
under mild heat (30 ° C) medium salts takes its thermal decomposition to ammonia and acid salt: (NH4) 2CO3 → 2 NH4HCO3 + NH3.
If the water dissolving carbon dioxide and ammonia, it is also possible to obtain the ammonium salt of the acid: NH3 + CO2 + H2O → NH4HCO3.
Application
Ammonium bicarbonate is widely used in the food industry: the role played by the chemical leavening agent in the manufacture of confectionery and bakery products.It is known that for lifting unleavened dough is also used sodium bicarbonate NaHCO3.But its application is less effective, because the tightening or kneading until exposure baking results in more rapid removal of the formed by the reaction of carbon dioxide with an acid, and in this case, the dough will not lush and easy.
Ammonium bicarbonate is used for tanning and in dyeing textile fabrics: in the process of removing the unfixed dye (or stripping), a mixture of ammonium salts, including ammonium bicarbonate.
substance used in agriculture as a preservative feed (slow down the processes of decay, thereby increasing the safety), as well as fertilizer for potatoes, fodder and vegetables.Use it on the properties of slowing or stopping the nitrification of soil.
Ammonium bicarbonate is used in the uranium mining and metallurgical industries, as well as in medicine (in the production of vitamins).In organic synthesis, a raw material for the production of chemicals, such as ammonium salts.
