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. Let’s check below what is the difference between strong and weak acids and bases.

Difference between Strong and Weak Acids and Bases

Strong Acids and Bases

An acid or a base is 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.

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:                HClO 4

Chromic acid:                   H 2 CrO 4

Tetrafluroboric acid:         HBF 4

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

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.

Examples of Weak Acids with their Formula and Acid ionization constant K a

Weak acid                Formula                               Lonization constant

Formic acid               H 2 CO 2                                1.77 x 10 -4

Acetic acid                H 3 CCOH                              1.75 x 10 -5

Hydrocyanic acid      HOCN                                     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                               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                      C 6 H 5 NH 2                            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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