On the strength of acid
Acids of the world, there are many categories, different strengths and weaknesses, and their properties are different. To distinguish the strength of an acid (take Hf acid as an example), it is necessary to investigate its essence.

Strong acidic ones can mostly dissociate completely in water, releasing a large number of hydrogen ions. Its degree of ionization is high, and the resulting solution has a large concentration of hydrogen ions, which is highly corrosive and reactive chemically. Such as strong acids, they can react rapidly when encountering metals, generating hydrogen gas and corresponding salts.

Weak acids are not the case, only partially dissociate in water, and the release of hydrogen ions is limited. The concentration of hydrogen ions in its solution is relatively low, and the chemical reactivity is relatively mild. Although it can also react with metals or bases, the rate is slower than that of strong acids.

To break the strength of Hf acid, first look at its dissociation status in water. If most of the Hf acid molecules dissociate into ions and produce high concentrations of hydrogen ions, it is a strong acid; if only a small amount of molecules dissociate and the concentration of hydrogen ions is low, it is a weak acid.

Furthermore, it depends on the intensity of its reaction with metals, alkalis and other substances. If it encounters metals, it will react violently in an instant, sparks will splash, and gas production will be rapid. This is a sign of strong acid; if the reaction is slow, it will take a long time to see slight effect, and it will also appear as a weak acid.

The pH value of its solution can be measured. Those with low pH value have high hydrogen ion concentration and high possibility of strong acid; pH value is slightly higher, low hydrogen ion concentration, or weak acid.

The strength of acid can not be determined at one end, and it is necessary to comprehensively consider multiple factors such as dissociation degree, reactivity, pH value, etc., in order to obtain a definitive conclusion.