Question

What do you understand about alkali? Give two examples of weak alkalis?

Answer 1

The name "alkali" comes from the Arabic word al qaly (or alkali), which refers to the original source of alkaline substances, calcined ashes (see calcination). Potash, a water-extract of burned plant ashes made primarily of potassium carbonate, was mildly basic. This material was heated with calcium hydroxide (slaked lime) to generate caustic potash (potassium hydroxide), a significantly more strongly basic chemical.

Complete answer:
An alkali is a basic ionic salt of an alkali metal or an alkaline earth element in chemistry. A base that dissolves in water is also known as an alkali. The pH of a soluble base solution is more than $7.0$ . In English, the adjectives alkaline and alkalescent are frequently used as synonyms for basic, especially for bases soluble in water. Because alkalis were the first bases found to obey the Arrhenius definition of a base, and they are still among the most frequent bases, this broad use of the term is likely to have arisen.
Alkalis are all Arrhenius bases, meaning they dissolve in water and produce hydroxide ions $\left( {OH} \right).$ The following are some of the most common qualities of alkaline aqueous solutions:
A pH of $7.1$ or above is required for moderately concentrated solutions (greater than $103{\text{ }}M$ ). They will change the hue of phenolphthalein from colourless to pink as a result of this.
Caustic solutions are those that have been concentrated (causing chemical burns).
Due to the saponification of fatty compounds on the skin's surface, alkaline solutions seem slippery or soapy to the touch.
Although most alkalis are water soluble, others, such as barium carbonate, are only soluble when combined with an acidic aqueous solution.
Ethanoic, citric, and carbonic acids are examples of weak alkalis.

Note:
The concept of an alkali has a number of different definitions. Alkalis are typically thought of as a subset of bases. Typically, one of two subgroups is chosen.
An alkali metal or alkaline earth element's basic salt ( $Mg{\left( {OH} \right)_2}$ (magnesium hydroxide) is included, but $N{H_3}$ (ammonia) is not.)
Any base that generates hydroxide ions when dissolved in water, or the solution of a base in water.
(This includes $Mg{\left( {OH} \right)_2}$ as well as $N{H_3}$ .)
An "Arrhenius base" is the name given to the second subset of bases.