Is salt an acid?



Under the Salt formation reactions one understands different chemical reactions that contain a salt as a product. In order to produce a certain salt one has to look for reactants that deliver the two components of a salt. This includes a cation (metal, ammonium ion) and an anion of an acid.

The production of a salt becomes more complicated if several different anions and cations are contained in one salt.

Neutralization of acid and alkali

During neutralization, a lye reacts with an acid to form salt and water. The components in the acid (oxonium ions) and the lye (hydroxide ions), which make up their acidic and alkaline properties, react with each other to form water.

Danger: Highly concentrated solutions can heat up so much during neutralization that the hot solution can even splash.

General equation of reaction
Acid + lye → salt + water
example 1
Hydrochloric acid + sodium hydroxide solution → sodium chloride + water
HCl (aq) + NaOH (aq) → NaCl (aq) + H2O (l)
Example 2
Sulfuric acid + barium hydroxide → barium sulfate + water
H2SO4(aq) + Ba (OH)2(aq) → BaSO4(s) + 2H2O (l)

Synthesis from the elements

A binary salt (consisting of a metal ion and a non-metal ion) can be produced by a direct reaction of the two elements. A redox reaction takes place with the transfer of electrons from the metal to the non-metal. The reaction can be very violent and only occurs if the non-metal ion is an element of main group 7.

General equation of reaction
Metal + non-metal → salt
example 1
Sodium + chlorine → sodium chloride
2Na + Cl2 → 2NaCl
Example 2
Magnesium + iodine → magnesium iodide
Mg + I2 → MgI2

The ion transfer from sodium to chloride is actually endothermic, but since the entire reaction is exothermic, other reactions must also play a role in salt formation:

Namely the sublimation energy, ionization energy, binding energy, electron affinity and lattice energy.

Metal with acid

If the metal is not too noble, it reacts with an acid, releasing hydrogen. This can arise because electrons are transferred from metal atoms to the oxonium ions of the acid. The resulting acid residue ions form the salt with the metal ions during evaporation.

General equation of reaction
(base) metal + acid → salt + hydrogen
example
Magnesium + hydrochloric acid → magnesium chloride + hydrogen
Mg + 2HCl(aq) → MgCl2 (aq) + H2 (g)

Index (aq) indicates that it is HCl dissolved in water.

Metal oxide with acid

The metal oxides also react with acid. In contrast to the reaction of metals with acids, there is no redox reaction here. It is a rearrangement. This creates several water molecules from the oxygen in the oxide and oxonium ions.

General equation of reaction
Metal oxide + acid → salt + water
example 1
Sodium oxide + hydrochloric acid → sodium chloride + water
N / A2O + 2HCl → 2NaCl + H2O
Example 2
Copper oxide + sulfuric acid → copper sulfate + water
CuO + H2SO4 → CuSO4 + H2O

Non-metal oxide with lye

According to the above reaction, oxides of non-metals combine with alkalis to form salts:

General equation of reaction
Non-metal oxide + lye → salt + water
example
Calcium hydroxide + carbon dioxide → calcium carbonate + water
Ca (OH)2 + CO2 → CaCO3 + H2O

Note: Basically, the options for non-metal oxide and alkali or metal oxide with acid are the same as for acid and alkali, since non-metal oxides form acids with water and metal oxides form bases with water.

Salt with acid

According to the principle ... The stronger acid drives the weaker one out of its salt ... you can also make another salt from a salt and an acid.

General equation of reaction
Salt + stronger acid → salt of stronger acid + weaker acid
example
Sodium carbonate + hydrochloric acid → sodium chloride + carbonic acid
N / A2CO3 + 2HCl → 2NaCl + H2CO3

Salt with salt

In an aqueous solution, two salts can "exchange" ions. This creates two new salts. However, this only works under the condition that one of the two salts formed is sparingly soluble in water. It forms a precipitate.

General equation of reaction
Saline A + Saline B → Saline (solution) C + Saline D
example
Sodium chloride + silver nitrate → silver chloride + sodium nitrate
NaCl(aq) + AgNO3 (aq) → AgCl(s) + NaNO3 (aq) (White precipitation)

Uses: Such reactions can be used to identify anions or cations through the color or solubility of the precipitate in certain substances.

Category: Chemical reaction