"Acidity" refers to the number of bases in a molecule or the number of hydroxyl group -OH in a chemical equation. For example, NaOH and KOH have a base acidity of 1, Ca(OH)2 and Ba(OH)2 have a base acidity of 2, and Al(OH)3 has a base acidity of 3. These are expressed as monoacidic base, diacidic base, and triacidic base, respectively. Acidities of 2 or higher are also grouped together and referred to as polyacidic base. Acidity is also sometimes called "acid level." As a simple example, the juice from a mandarin orange is primarily made up of sugar, acid, and water.
Pickling liquid is primarily made up of sugar, salt, acid, and water.
Acidity expresses the amount of "acidic components" in mandarin orange juice or pickling liquid as a ratio (%).
Generally, acidity represents the number of grams of acidic components in 100 mL of mandarin orange juice or pickling liquid as a percentage. Internationally, it usually represents the number of grams of acidic components in 1,000 mL (1 L) as a percentage.
Acidity expresses in a ratio what portion of fruit juice or liquid condiments is made up of acidic components, so it is intuitive and easy to understand.
pH expresses the degree of acidity and alkalinity as a value. Purified water is neither alkaline nor acidic, so the pH level is the neutral point of 7. Juice and liquid condiments contain acid, so they are acidic.
In acidic liquids, acidity levels and pH levels are not unrelated, but when the acidity changes greatly, the pH level changes only a little.
pH is used as one standard to measure the properties of water. In English, it is read "pee-eych," while in German it is read "pay-ha."
Scientifically speaking, pH expresses the amount of hydrogen ion concentration (H+) in a liquid. If the concentration of hydrogen ions (H+) in the liquid is high, it is acidic. If the concentration is low, it is basic (alkaline). This means that when the concentration of hydrogen ions is measured, the acidity, neutrality, and alkalinity, as well as the respective degree can be discovered.
The pH value has a scale of 0 to 14, where 7 is neutral and any value below 7 is increasingly more acidic as it decreases in value, and where any value above 7 is alkaline and alkalinity increases as the value increases. Bitter-tasting liquids such as vinegar, juice, and lye (ash dissolved in water) are alkaline. Neutrality (pH 7) means that the hydrogen ion concentration is 10-7 (0.0000001) moles per liter.