All alkalis are bases but all bases are not alkalis.

The statement "All alkalis are bases but all bases are not alkalis" highlights the relationship between alkalis and bases. To understand this statement, it is important to have a clear understanding of what alkalis and bases are.

What are bases?
- Bases are substances that can accept protons or donate electrons.
- They are chemical compounds that release hydroxide ions (OH-) in aqueous solutions.
- Bases can neutralize acids and form salts.
- Examples of bases include sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH)2), and ammonia (NH3).

What are alkalis?
- Alkalis are a specific type of bases that are soluble in water.
- They have a pH greater than 7 and can conduct electricity in aqueous solutions.
- Alkalis also release hydroxide ions (OH-) when dissolved in water.
- Common examples of alkalis include sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH)2.

Explanation of the statement:
The statement "All alkalis are bases but all bases are not alkalis" indicates that alkalis are a subset of bases. In other words, all alkalis can be classified as bases, but not all bases can be categorized as alkalis. This distinction arises due to the solubility of the substances in water.

All alkalis are bases:
- Alkalis are a specific type of bases that are soluble in water.
- They possess the characteristic of releasing hydroxide ions (OH-) in aqueous solutions.
- Alkalis have a pH greater than 7 and can conduct electricity in water.
- The presence of hydroxide ions makes them effective at neutralizing acids and forming salts.

All bases are not alkalis:
- While all alkalis are bases, not all bases are alkalis.
- Bases can be classified into two categories: soluble and insoluble bases.
- Soluble bases, which include alkalis, dissolve completely in water.
- Insoluble bases, on the other hand, do not dissolve in water and do not exhibit the properties associated with alkalis.
- Examples of insoluble bases include metal oxides, metal hydroxides, and metal carbonates that do not readily dissolve in water.

In conclusion:
The statement "All alkalis are bases but all bases are not alkalis" emphasizes that alkalis are a specific subset of bases. Alkalis possess the characteristics of bases, including the ability to release hydroxide ions in water and neutralize acids. However, not all bases are soluble in water and therefore cannot be classified as alkalis. By understanding the distinction between alkalis and bases, we can better comprehend the properties and behavior of these substances in different chemical reactions and contexts.

It means that all alkalis are bases but some bases are not alkalis.