Difference between Alkali and Base, Examples, Definitions
Alkali is a word derived from Arabic that means calcined ashes. It is a base that dissolves in water. The acid and base are classified based on taste. Acid tastes sour and base tastes bitter. This classification is given by Arrhenius. Alkalis are the bases that dissolve in the water. All alkalis are bases but all bases are not alkali. The alkali is used for alkali metal hydroxide because they easily dissolve in water to form OH ions. An alkali converts red litmus to blue and is bitter to taste. The pH of the alkali solution is more than 7. As compared to other metals, an alkali has low density. They are good conductors of electricity and heat.
Alkalis are kept in a solution like kerosene because they are reactive metals that react with the atmosphere when coming outside. They have low melting and boiling point and are soft metals due to which it is easy to cut them using a knife.
Examples of Alkalis are:
Sodium hydroxide (NaOH) — caustic soda
Potassium hydroxide (KOH)— caustic potash
Calcium hydroxide Ca(OH)2 — limewater
There are three definitions of Bases according to different concepts:
- Arrhenius Concept - The compound which furnishes OH in aqua solution is known as base. This definition covers all the hydroxides of alkaline earth metal and alkali metal. for example, NaOH, Ca(OH)2, etc. Bases are the compound which reacts with acid and forms a salt.
- Bronsted-Lowry Concept - According to this concept, the compound which is capable of proton accepting is known as base. Through this definition cover many bases but still some are rest because not all bases remove H+ ions.AlCl3 acts as lewis acid but it doesn't have H+ to remove.
- Lewis Concept - According to lewis's concept, the compound which donates a lone pair of electrons is known as base. For Eg, NH3 is lewis's base. It extracts protons and lies stable.
Bases can be strong or weak. Those bases which are strong can easily burn the skin. Some of the common bases are ammonia, caustic soda, baking soda, etc. These are bitter and odorless.
Difference Between Alkali and Base
The difference between an alkali and a base is:
- Alkali compounds are types of bases that dissolve in water whereas the base neutralizes the acid.
- All alkali are bases but all bases are not alkalis.
- Alkali is used for metals of group 1 in the periodic table whereas the base is a compound having OH ions.
- In alkali metal, Group 1 metals of the periodic table are their ionic compound whereas any compound can be ionic or covalent.
- Alkali metals form carbonates and hydroxides whereas bases form hydroxide or lone pairs.
- Examples of Alkali are NaOH, KOH, Ca(OH)2, and examples of bases are NaOH, KOH, Al(OH)3.
- Alkali metals are shiny and soft whereas bases are slippery.
- The strength of Alkali metals can depend on the nature and concentration of ionic salt whereas the base strength depends on the concentration of hydroxide ions