Acids,.bases & salts.. class 10 science

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CHARACTERISTIC PROPERTIES OF ACIDS:



• Sour Taste:   Acids have sour taste.
• Action on litmus:.  Acids turn blue litmus solution to red.
• Action on methyl Orange:.  When a drop of methyl Orange is added to an acidic solution, it turns solution red.
• Reaction with Metals to form Hydrogen gas:.  When acids react with active metals a salt is formed with the evolution of hydrogen gas.
Metal + Acid  ➡ Metal salt + hydrogen gas
    Zn  +    2HCl      ➡      ZnCl2  + H2

•Reaction with Bases to form salt and water:

     Acid +   Base    ➡   Salt   +   Water
    HCl   +   NaOH  ➡    NaCl  +  H2O
The reaction between an acid and a base to give a salt and water is known as neutralization reaction.

•Reaction with Metal oxides to form salt & water:

     CuO  +  2HCl  ➡   CuCl2 +   H2O

• Conduction of Electricity.

• Corrosive Nature.


CHARACTERISTICS PROPERTIES OF BASES:

• Bitter taste:. Bases posses a bitter taste.
• slippery or soapy touch:  Bases possess a slippery touch like soaps.
• Action on Litmus: Bases turn red litmus blue.
Action on phenolphthalein:  Bases turn phenolphthalein solution pink.
• Reaction with Metals to form Hydrogen gas:  When bases react with active metals, a salt is formed along with liberation of hydrogen gas.
   Metal + Base  ➡  Metal salt + Hydrogen gas
     2NaOH  +  Zn   ➡   Na2ZnO   +  H2

• Conduction of Electricity.
• Corrosive Nature of Bases.

The bases which are soluble in water and give hydroxide ions in the aqueous solution are known as Alkalies.

STRENGTHS OF ACIDS & BASES:

          Strong and weak Acids

• Strong Acids are those which dissociate completely in water and hence give a large amount of hydrogen ions.
 
• weak Acids are those which ionise partially in water and thus give a small amount of hydrogen ions.

         Strong and weak Bases

• Strong bases are those which ionise completely in water and give a large amount of hydroxide ions.

• Weak Bases are those which ionise partially to produce a small amount of hydroxide ions.

Note: The strength of an acid or base is measured on a scale of numbers called pH scale












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