Question

Distinguish between base and alkaline

Answer 1

• Bases are substances that react with acids and neutralise them. They are usually metal oxides, metal hydroxides, metal carbonates or metal hydrogen carbonates. Many bases are insoluble - they do not dissolve in water. If a base does dissolve in water, we call it an alkali.
• Alkaline solution/compound is the same as a basic solution/compound. But you can specify "alkali" to refer to those bases that are soluble in water and that are salts of alkaline or alkaline earth metals too.
• A basic substance is usually one or two metal atoms bonded with an oxygen atom to make OXIDES.
  An alkaline substance is like a base, but it involves hydrogen in the alkali molecule, so that it forms HYDROXIDES.

So, in general, Bases are Oxides and Alkalis are Hydroxides.

• Alkaline are those which can give OH- ions when dissolved in water
  but basic are those which react with acid to give water and salt
  so compounds containing OH- termed as Alkaline like NaOH, KOH etc on other hand CaO , Na2O are basic but not alkaline
• Any basic substance has a power of hydrogen, or pH, above 7.0, the pH of pure water. Acidic substances have a pH of below 7.0. Basic substances are basic because they are capable of accepting hydrogen ions, and hydrogen ions are what give acids their caustic properties.