Bases: Have you thought why the turmeric stain on your white shirt turns to red when it is washed with soap? Well the reason behind this is that the soap solution is basic. You might already know that acids are sour in taste and change the colour of blue litmus to red, while bases are bitter and change the colour of the red litmus to blue. Let us find out more about bases.
What is a Base?
Put simply, a base is a substance that forms water and salts when reacted with acid. NCERT defines bases as, ‘’Substances which are bitter in taste and feel soapy on touching are known as bases. The nature of such substances is said to be basic.’’ Students might be aware that bases are substances that are able to neutralize the acid after reacting with hydrogen ions.
Some examples of bases are- Sodium hydroxide (caustic soda), Sodium carbonate (washing soda), Potassium hydroxide, Calcium carbonate etc.
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Types of Bases
Bases are usually categorised into two parts on the basis of their solubility in water. These are- water soluble bases i.e. alkali and water insoluble bases i.e. base.
Water soluble bases i.e. alkali- Alkalis are bases which are soluble in water. Some alkali metals are lithium, sodium, and potassium. Other examples of alkalis are: sodium hydroxide, calcium hydroxide, potassium hydroxide, lithium hydroxide, etc.
Water insoluble bases i.e. base- Bases are usually insoluble in water. Students must note that all bases are bases but not all bases are alkalis. For example, the oxides of alkali metals, like sodium oxide, dissolve in water to form hydroxides. Some oxides of alkaline earth metals are both slightly soluble in water and are slightly alkaline.
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Properties of Bases
| Bases have a bitter taste. They have a soapy touch. Bases have a pH value greater than 7. They conduct electricity in solution. Indicator colour changes from red to blue litmus paper. Bases have OH– ions. They react with acid to form salts and water. They neutralise acids. |
Students are advised to prepare for the examination with the help of NCERT books as these books help students to gain an understanding of concepts and strengthen their basics. NCERT Books are published based on the latest CBSE syllabus. These books are recommended due to their explanation of even difficult topics in simple and clear language. Students can perform well in exams by referring to the NCERT Books.
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