Acids, Bases and Salts- II

Acids, Bases and Salts - II

Chemical Properties of Acids and Bases

 1)      Reactions of Acids and Bases with metals

a)   Acid when reacts with metal form salts and hydrogen gas is liberated.

Zn	+	H2SO4	→	ZnSO4	+	H2 (↑)
Zinc		Sulphuric Acid		Zinc sulphate		Hydrogen gas

    Observation – bubbles are observed on the surface of Zn metal. Gas when passed through soapy water forms bubbles and when tested with burning candle, it produces POP sound.
b)     Base when reacts with a metal it forms a salt ad hydrogen gas is liberated.

Zn	+	NaOH	→	Na2ZnO2	+	H2
Zinc		Sodium hydroxide		Sodium zincate		Hydrogen gas

2)            Reaction of metal carbonates and metal hydrogen carbonates with acids

     Metal carbonates and metal hydrogen carbonates when reacts with acids they form their respective salt, water and carbon dioxide gas is liberated out. For example,

a)                   Sodium carbonate when reacts with hydrochloric acid it forms sodium chloride, water and carbon dioxide gas is liberated.

Na2CO3	+	2HCl	→	2NaCl	+	H2O	+	CO2 (↑)
Sodium  carbonate		Hydrochloric acid		Sodium chloride		Water

b)                 Sodium hydrogen carbonate when reacts with hydrochloric acid it forms sodium chloride, water and carbon dioxide gas is liberated.

NaHCO3	+	HCl	→	NaCl	+	H2O	+	CO2 (↑)
Sodium  bicarbonate		Hydrochloric acid		Sodium chloride		water

On passing the carbon dioxide gas through lime water, it turns milky due to the formation of calcium carbonate. Ca(OH)2      + CO2 → CaCO3 + H2O Later on passing excess of carbon dioxide, white precipitate dissolves and calcium bicarbonate is formed which is soluble in water. Ca(OH)2      + CO2 + H2O → Ca(HCO3)2

3)      Reaction of an acid and a  base

An acid reacts with a base to give a salt and water, this reaction is known as neutralisation reaction.

NaOH

+

HCl

→

NaCl

+

H2O

          4)      Reaction of metallic oxides with acids

Metallic oxides are basic in nature. They react with acids to form salt and water.

Metal oxide	+	Acid	→	Salt	+	Water
CuO	+	2 HCl	→	CuCl2	+	H2O
Copper oxide		Hydrochloric acid		Copper chloride		Water
				(blue - green)

         5)      Reaction of non – metallic oxides with bases

Non – metallic oxides are acidic in nature. They react with bases to form salt and water.

CO2

+

Ca(OH)2

→

CaCO3

+

H2O