In your daily life, you use different types of soaps and detergents. Washing and cleaning clothes are done with their help. These substances contain alkalis, which are chemically hydroxides or oxides of metals and react with water to form hydroxides.
Oxide compounds are formed by the reaction of elements with oxygen. Hydroxides of metals are compounds in which one or more hydroxyl (-OH) groups are attached to the metal. Metallic oxide can be represented by M(OH)n in which n is the valence of metal M.
Common examples of alkalis are sodium hydroxide (caustic soda), calcium hydroxide, and magnesium hydroxide.
Properties of Alkalis
1. Smooth on touch: You must have noticed that soap and detergents appear smooth on touching. In fact, this is the common property of alkalis, due to which they appear smooth on the sieve.
2. The taste of alkalis is bitter.
3. Effect on Litmus
- Blue litmus: There is no color change in the litmus when the blue litmus of alkali is processed.
- Red litmus: Red litmus turns blue under the influence of alkalis.
4. Effect on phenolphthalein solution: Pink color is obtained by adding a few drops of phenolphthalein indicator in an alkaline solution. Indicators are substances that give different colors with acids and bases.
5. Effect on Methyl Orange: Methyl Orange is another indicator. It has no effect on the color of alkaline solution.
Uses of Alkalis
- Caustic soda or is used in soap making, paper making and petroleum refining.
- Lime (calcium oxide) is used to neutralize (eliminate) the acidic soil properties. It is also used in whitening.
- Ammonium hydroxide is used in the laboratory. It is also used in dry cleaning to remove dark stains from clothes.