The pH range of alkalis typically spans from $7$ to $14$.

Alkalis are defined as substances that can accept protons or donate pairs of electrons. They are located at the higher end of the pH scale, which contrasts with acids that have a pH range from $0$ to $7$. The pH scale measures the acidity or alkalinity of a substance, ranging from $0$ to $14$, with $7$ representing a neutral point. Substances with a pH greater than $7$ are classified as alkaline or basic, while those with a pH less than $7$ are labeled as acidic.

Alkalis are characterized by their bitter taste and slippery texture. They have the ability to change red litmus paper to blue, a clear indication of their basic properties. Common examples of alkalis include baking soda (sodium bicarbonate), ammonia, and lye (sodium hydroxide). All of these substances exhibit a pH greater than $7$, confirming their alkaline nature.

The strength of an alkali can vary significantly, much like the strength of acids. Strong alkalis, such as sodium hydroxide, have a pH that approaches $14$. These substances are highly reactive and can pose safety risks if not handled properly. In contrast, weak alkalis, such as baking soda, have a pH closer to $7$. They are less reactive and generally safer to use.

It is crucial to note that the pH scale is logarithmic, which means that each unit change represents a tenfold difference in acidity or alkalinity. For instance, a substance with a pH of $8$ is ten times more alkaline than one with a pH of $7$, while a substance with a pH of $9$ is one hundred times more alkaline than one with a pH of $7$. This logarithmic nature explains why even minor changes in pH can significantly affect the characteristics of a substance.