Acid is basically a chemical that dissolves with water quickly and forms positively charged hydrogen ions. In other words, acid accepts electrons and gives away protons or hydrogen ions. In chemical terms, an acid is an ionic compound (a compound that has a negative or positive charge) that when exposed to water breaks apart and forms hydrogen ions. An acid’s strength or acidity is determined by the number of hydrogen ions.

The higher the hydrogen ion concentration, the stronger is the acid. On a pH scale, an acid has a pH number below 7, which means it’s acidic or has a higher hydrogen concentration than an alkaline such as water. And this low pH value means acid can turn water sour, change colors litmus paper to red from blue, react with base substances to form salts, etc.  

Acids are corrosive in nature and even the weakest acids cannot be preserved in metal boxes or containers, thanks to the caustic relationship between acids and metals. Acids can cause metals such as iron to rust or corrode. As aforementioned, acids turn liquids sour. Even liquids with weak acids – such as vinegar and lemon juice – taste sour. Citrus fruits such as lemon taste sour because they have citric acid. Similarly, acetic acid causes vinegar to taste sour.

Types

Acids are basically categorized as weak or strong acids. A strong acid completely dissolves when put in solutions, whereas a weak acid dissolves partially. This is because strong acids have increased hydrogen ion concentrations. Upon water exposure, both strong and weak acids make hydrogen ions. A strong ion would ionize completely and may turn into sulfuric acid, hydrochloric acid, or nitric acid.

A weak acid, on the other hand, when introduced to water could form a mixture that has a higher pH level compared to a strong acid. The mixture comprises both acid and liquid. Ethanoic acid is one such acid that’s not as strong or acidic as sulfuric or nitric acid. Some other weak acids are acetic acid, citric acid, carbonic acid, phosphoric acid, and oxalic acid.