The pH usually ranges from 0 to 14 (although it can also be negative or above 14), with 7 in the middle. Alkali can be regarded as a substance with a pH value higher than 7, and the alkali that is soluble in water is called a soluble alkali. Common soluble bases include ammonia and baking soda.
In 2009, a study by Swedish scientists found that alkaline substances can damage teeth just as much as acids such as fruit juices, so the previous practice of "brushing your teeth with baking soda to protect your teeth by neutralizing the acids" seems out of fashion.
pH is actually a logarithmic value, so every 1 increase in pH represents a tenfold increase in alkalinity, and vice versa. Thus, a solution with a pH of 14 is ten times more alkaline than a solution with a pH of 13, while a solution with a pH of 1 is ten times more acidic than a solution with a pH of 2. Strong and weak acidsNowadays, we think of acids as proton donors and bases as proton acceptors, (note that in this context, protons refer to ions formed after a hydrogen atom loses electrons, so the theory is simply that acids provide hydrogen ions and bases accept hydrogen ions.) The acidity of an acid.
Strength is determined by its ability to deliver protons.
The acetic acid (chemical name acetic acid, CH COOH) in the vinegar used to dip dumplings is a weak acid because there are always many acetic acid molecules that have not lost their protons at any given moment. Or more precisely, protons are constantly ionized from acetic acid molecules.
It is constantly recombined to form a chemical equilibrium, and the hydrochloric acid (HCI) that David has studied is quite capable of supplying protons. All the hydrochloric acid molecules that are dissolved in water are broken down into hydrogen ions and chloride ions, or in other words, it is completely ionized in water.
The strength of an acid is independent of its concentration. If the same number of strong and weak acid molecules are dissolved in the same amount of water, the strong acid (e.g. hydrochloric acid) will release more hydrogen than the weak acid, so the concentration of hydrogen ions in the solution of the former will also be higher. But if you add enough water to dilute the hydrochloric acid, it can also make it weaker acidic than vinegar. In chemistry, the strength of an acid is generally expressed in terms of pH. It is important to note that a smaller pH means a higher concentration of hydrogen ions. In general, the higher the concentration of the acid, the more acidic it is and the lower the pH.