• Action of Acids with metal Carbonates and metal bicarbonates

      Metal Carbonate + Acid → Salt + Carbondioxide + Water

      Na₂CO_3(S) + 2HCl_(aq) → 2NaCl_(aq) + H₂O(l) + CO_2(g)

     Metal bicarbonate + Acid → Salt + Carbondioxide + Water

     NaHCO₃ + HCl → NaCl + CO₂ + H₂O

• Lime water Test : On passing the evolved CO₂ gas is Passed through lime water,

• Reaction of acids and bases with each other.

• Neutralisation Reactions

     Base + Acid → Salt + Water

     NaOH_(aq) + HCl_(aq) → NaCl_(aq) + H₂O(l)

Neutralisation reaction : The reaction between an acid and a base to give salt and waste is called as neutralization reaction takes place when the effect of a base is nullified by an acid and vice versa to give salt and water.

• Reactions of metal oxides with acids

Note : Appearance of blue green colour of the solution because of formation of CuCl₂.

Metallic oxides are said to be basic oxides because they give salt and water on reacting with acids.

• Reaction of Non Metallic Oxide with Base

     Non metallic oxide + Base → Salt + Water

     Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

Note : Non Metallic oxides are said to be acidic in nature because on reacting with a base they produce salt and water.

• All acidic solutions conduct electricity because of formation of (H⁺ions in eq, solution.)

      Refer activity 2.3 on page 22 of NCERT Book

     – Glowing of bulb indicates that there is a flow of electric current through the solution.

• Acids or bases in a Water Solution

   Acids produce H⁺ ions in the presence of water

   HCl + H₂O → H₃O⁺ + Cl^–

   H₃O⁺ – Hydronium ion.

               – H⁺ion cannot exist alone. It exists as H⁺(aq) or (H₃O⁺) hydronium ion.

   H⁺ + H₂O → H₃O⁺

– Bases provide (OH^–) ions in the presence of water

• Alkalis

  All bases donot dissolve in water. An alkali is a base that dissolves in water. Common alkalis are

    NaOH           Sodium hydroxide

    KOH             Potassium hydroxide

    Ca(OH)₂     Calcium hydroxide

    NH₄OH      Ammonium hydroxide

    Note : All alkalis are bases but all bases are not alkalis.

• Precaution must be taken while mixing acid or base with water. The acid must always be added to water with        constant stirring as it is a highly exothermic reaction.

    When an acid or a base is mixed with water they become dilute. This results in the decrease in the           concentration of H₃O⁺ or OH^– per unit volume in acids and bases respectively.

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