A classification of acids and bases in chemistry depends on the ionization force of these substances in aqueous medium. A) Yes:
- an acid and a base are strong when they are completely ionized, that is, in the ionization process they are completely transformed into cations or positive ions and into anions or negative ions.
- On the other hand, an acid and a base are weak when they are partially ionized in water, that is, in solution there will be a proportion of cations, another proportion of anions and another proportion of undissociated molecules.
| Strong acids and bases | Weak acids and bases | |
|---|---|---|
| Definition | Substances that completely ionize in solution. | Substances that partially ionize in solution. |
| Ionization | Complete | Partial |
| Elements in aqueous solution | Cations and anions in the same concentration. | Cations, anions and molecules in different proportions. |
| Ionization constant | Elevated | Small |
| Examples |
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Index
Strong acids and bases
An acid or a base are strong when they dissociate completely in an aqueous medium , that is, the ionization process is complete and the solution will contain the same concentration of anions as cations.
How do you ionize an acid and a strong base?
A strong acid, such as hydrochloric acid HCl, ionizes in the following way:
A strong base, such as sodium hydroxide NaOH, ionizes in the following ways:
Examples of strong acids and their formulas
| Strong acids | Formula |
|---|---|
| Hydrochloric acid | HCl |
| Sulfuric acid | H 2 SO 4 |
| Nitric acid | HNO 3 |
| Hydrobromic acid | HBr |
| Perchloric acid | HClO4 |
| Chromic acid | H2CrO4 |
| tetrafluoroboric acid | HBF4 |
Examples of strong bases and their formulas
| Strong base | Formula |
|---|---|
| Sodium hydroxide | NaOH |
| Lithium hydroxide | LiOH |
| Potassium hydroxide | KOH |
| Rubidium hydroxide | RbOH |
| Cesium hydroxide | CsOH |
| Calcium hydroxide | Ca(OH)2 |
| Barium hydroxide | Ba (OH) 2 |
| Strontium hydroxide | Sr(OH)2 |
| Aluminum hydroxide | Al(OH)3 |
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Weak acids and bases
An acid or a base is weak when it is partially ionized in aqueous solution , that is, non-ionized ions and molecules are found in the solution.
How do you ionize an acid and a weak base?
A weak acid, such as acetic acid CH 3 COOH, ionizes as follows:
The equilibrium of this reaction is expressed by the two arrows in opposite directions.
When a weak acid dissociates or ionizes, an equilibrium is established between the species present in the solution; This can be expressed by an acid ionization constant :
The ionization constant is nothing more than the ratio between the multiplication of the concentration of the products over the multiplication of the concentration of the reactants.
A weak base, such as NH 3 ammonia , ionizes as follows:
When a weak base dissociates or ionizes, an equilibrium is established between the species present in the solution; This can be expressed by an ionization constant of the base :
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Examples of weak acids with their formula and acid ionization constant K a
| Weak acid | Formula | Ionization constant |
|---|---|---|
| Formic acid | H2CO2 | 1,77 x 10-4 |
| Acetic acid | H3CCOH | 1,75 x 10-5 |
| Hydrocyanic acid | THIS | 3,30 x 10-4 |
| Hydrogen cyanide | HCN | 6,20 x 10-10 |
| Hypochlorous acid | HOCl | 3,50 x 10-8 |
| Nitrous acid | HNO 2 | 4,00 x 10-4 |
| Lactic acid | HC 3 H 5 O 3 | 1,40 x 10-4 |
| Carbonic acid | H 2 CO 3 | 4,30 x 10-7 5,60 x 10-11 |
| Boric acid | H 3 BO 3 | 5,80 x 10-10 1,80 x 10-13 3,00 x 10-14 |
Examples of weak bases with their formula and basic ionization constant K b
| Weak base | Formula | Ionization constant |
|---|---|---|
| Ammonia | NH 3 | 1,75 x 10-5 |
| Methylamine | CH 3 NH 2 | 4,38 x 10-4 |
| Ethylamine | C 2 H 5 NH 2 | 5,60 x 10-4 |
| Aniline | C6H5NH2 | 3,80 x 10-10 |
| Pyridine | C 5 H 5 N | 1,70 x 10-9 |
| Benzylamine | C 7 H 9 N | 2,20 x 10-5 |
| Sodium bicarbonate | NaHCO | 2,00 x 10-4 |
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