Question 1 Define a base. Give example?
Question 2 What are alkali?
Question 3 What is common in all bases?
Question 4 What are strong bases. Give example?
Question 5 What are weak bases. Give example?
Question 6 What happen when zinc granules are heated with sodium hydroxide solution?
Question 7 What happen when a base react with non-metal oxide?
Question 2 What are alkali?
Question 3 What is common in all bases?
Question 4 What are strong bases. Give example?
Question 5 What are weak bases. Give example?
Question 6 What happen when zinc granules are heated with sodium hydroxide solution?
Question 7 What happen when a base react with non-metal oxide?
Bases
Bases are those substances which have bitter taste. They turn red litmus to blue. Those bases which are soluble in water are called alkali.
For Example: NaOH, KOH, Mg(OH)2, NH4OH
A base is a substance which dissolves in water to produce hydroxide ion in solution.
NH4OH ⇌ NH4+ + OH–
NaOH(s) → Na+(aq) + OH–(aq)
When the solution of a base is diluted by mixing water to it, then the concentration of hydroxide ions decreases.
Strong Base
A base which completely ionises in water and produce large amount of hydroxide ions.
For Example : NaOH, KOH
For Example : NaOH, KOH
Weak Base
A base which partially ionises in water and produce small amount of hydroxide ions.
For Example : Mg(OH)2, Ca(OH)2
Properties of Bases
(1) They have bitter taste.
(2) They have soapy touch.
(3) They turn red litmus to blue.
(4) They conduct electricity.
(5) They react with some metals to form hydrogen gas.
(2) They have soapy touch.
(3) They turn red litmus to blue.
(4) They conduct electricity.
(5) They react with some metals to form hydrogen gas.
2NaOH(aq) + Zn(S) → Na2ZnO2(S) + H2(g)
Sodium Zincate
(6) Bases react with acid to form salt and water
2HCl(aq) + Mg(OH)2(s) → MgCl2(aq) + H2O(I)
(7) Bases react with non-metals oxide to form salt and water
Ca(OH)2 + CO2 → CaCO3 + H2O
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