BASES:
A base can be defined as a substance capable of releasing one or more OH- ions in aqueous solution. They are bitter in taste and soapy in touch.
A base which completely ionizes in water and thus produces a large amount of hydroxide ions(OH- ions ) is called a Strong Base / Strong Alkali. e.g. Sodium Hydroxide and Potassium Hydroxide.
A base which is partially ionized in water and thus produces a small amount of hydroxide ions is called a Weak Base / Weak Alkali. e.g. Ammonium Hydroxide.
Water soluble bases (like Sodium hydroxide and Potassium hydroxide ) are know as Alkalies .
List of some alkalies and their uses:
| Name | Commercial Name | Chemical Formula | Uses |
| Sodium Hydroxide | Caustic Soda | NaOH | In manufacture of soap, paper, pulp, rayon, refining of petroleum etc. |
| Potassium hydroxide | Caustic Potash | KOH | In alkaline storage batteries, manufacture of soap, absorbing CO2 gas etc. |
| Calcium Hydroxide | Slaked lime | Ca(OH)2 | In manufacture of bleaching powder softening of hard water etc. |
| Magnesium Hydroxide | Milk of Magnesia | Mg(OH)2 | As an antacid to remove acidity from stomach |
| Aluminum Hydroxide | Al(OH)3 | As foaming agent in fire extinguishers. | |
| Ammonium Hydroxide | Liquor ammonia | NH4OH | In removing greases stains from cloths and in cleaning window pane. |
Properties Of Bases :
The important properties of bases are:
- Bases have a bitter taste.
- Bases feels soapy in touch.
- Base turn red litmus blue. (Click here to know more about indicators and color change)
- Bases conduct electricity in solution (They are electrolytes): When bases are dissolved in water, it splits up in ions. Due to the presence of ions the base solution conduct electricity.
- Basis react with some metals to form hydrogen gas: Metals like Zinc, Tin and Aluminum react with strong alkalies like NaOH, Caustic Soda, KOH (Caustic Potash) to evolve hydrogen gas. (Click here for detailed experiment). Zn(s) + 2NaOH(aq) → Na2 + ZnO2(aq) + H2(g)
- Basis react with non metal oxides to form salt and water: Acids react with metal oxides, but bases react with oxides of non-metals to form salt and water.For e.g. 2NaOH(aq) + CO2(g) → Na2CO3(aq) + H2O
The Reaction of non metal oxides with bases to form salt and water shows that non metal oxides are acidic in nature.
Ab Padhega India
#AbPadhegaIndia – An initiative to help all the Class X Students get access to Quality Education for FREE.
