Bases

Just like Acids have a sour taste, Bases have a bitter taste . 

Bases are the chemical opposite of acids. They cancel the effect of acids. Let’s define it formally.

Definition of Base

A base is a substance which furnishes hydroxide ions (OH ^– ) when dissolved in water. 

For example

Sodium hydroxide NaOH (aq), in its aqueous solutions, dissociates as: 

                 NaOH (aq) ^⎯ → Na ⁺ (aq) + OH ^– (aq) 

Note : The term ‘alkali’ means water soluble bases

Some examples of bases are: 

1. Sodium hydroxide (NaOH) or caustic soda used in washing soaps. 
2. Potassium hydroxide (KOH) or potash used in bathing soaps. 
3. Calcium hydroxide (Ca(OH) ₂ ) or lime water used in white wash. 
4. Magnesium hydroxide (Mg(OH) ₂ ) or milk of magnesia used to control acidity (it is an antacid). 
5. Ammonium hydroxide (NH ₄ OH) used in hair dyes.

Properties of Bases:

1. Bases usually are bitter in taste
   
   
2. Bases can neutralise the effect of acids.
   
   
3. Bases feel soapy to touch
   
   
4. Bases and Indicators
   
   

   Indicator	Color in basic medium
   Litmus Paper	Red to Blue
   Phenolphthalein	Colorless
   Methyl orange	Red
   Turmeric	Turns from yellow to red .
5. Bases conduct electricity in water.
   
   
6. Bases react with some metals to form Hydrogen gas
   Bases + Metal ⎯→ Salt + Hydrogen gas
   Note : All metals do not react with base
   
   
7. Bases react with acids to form salt and water
   Base + Acid ⎯→ Salt + Water
   
   
8. Bases react with non-metal oxides to form salt and water
   Base + Non-metal Oxides ⎯→ Salt + Water