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ⓘ Alkali. In chemistry, an alkali is an aqueous solution with a pH value of more than 7. The word Alkali comes from the Arabic qali meaning from the ashes since a ..




                                     

ⓘ Alkali

In chemistry, an alkali is an aqueous solution with a pH value of more than 7. The word Alkali comes from the Arabic qali meaning from the ashes since ashes mixed with water used as cleaning products are made of alkali materials

An alkali is where a base is dissolved in water. Often it is the salt of an Alkali metal An alkali is the opposite to an acid and can be neutralised brought down to pH 7 by adding acid.

                                     

1. Characteristics

  • It feels soapy
  • Highly soluble can be dissolved in water
  • Turns red litmus paper blue
  • Can conduct electricity due to the presence of mobile ions
  • It is corrosive it can burn your skin away
  • They have a bitter taste
  • The higher the number is over 7 on the pH scale the stronger the alkali is.
  • Is blue or purple on universal indicator
                                     

2. Strength

Like acids, alkalis can be weak or strong, depending on the nature and the concentration of the ionic salt composing it. The strength of an alkali can be found using universal indicator. Also like acids, the strength of an alkali is rated using the pH scale.

For example, soap and toothpaste contain weak alkalis, while cleaning products often contain strong ones.

                                     

3. Uses of common Alkalis

  • Calcium hydroxide is used to neutralize acidic soil.
  • Ammonium hydroxide is used as a cleansing agent.
  • Sodium hydroxide is used to make paper, detergents and soap.
  • Potassium hydroxide is used by farmers to make acidic soil more alkaline so that plants will grow better in it, and is also used as the electrolyte in alkaline, Ni-Cd, and Ni-MH batteries.
                                     

4. Oxides and Hydroxides

Metal oxides and metal hydroxides are two types of base. When neutralised an acid is added they produce a salt and water. The type of salt produced depends on the acid and base.

                                     

5. Other websites

  • Alkali cleaning materials
  • In depth article on Alkalis - not recommended for Simple Wikipedia users
  • A revision site directed towards GSCE students
  • A distributor of Alkali Metals
  • Small article on Alkaline chemicals
  • Small in depth article on Alkali Metals