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(I) what is a neutralisation reaction? Give an example. (II) What colour change do you observe when CuO is added to dilute HCl, while stirring it? Write balanced chemical equation for the above reaction? (III) Why metallic oxides are said to be basic oxides? |
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Answer» (i) A neutralization reaction is when an acid and a base react to form water and salt and involves the combination of hydrogen ions and hydroxyl ions to generate water. The neutralization of a strong acid and strong base has a PH equal to 7. Example 1: When sodium hydroxide is added to hydrochloric acid, sodium chloride and water are formed. NaOH + HCl ⇾ NaCl + H2O Example 2: Milk of magnesia, which is a base, is given as antacid in the case of indigestion, to neutralize the more acid produced in the stomach. Mg(OH)2 + 2HCl ⇾ MgCl2 + 2H2O. (ii) When dilute HCl is added to copper oxide powder, blue- green colour is imparted due to the formation of copper chloride. The reaction is: 2HCl + CuO ⇾ CuCl2 + H2O This is a double displacement reaction. (iii) When metallic oxide reacts with water, it gives base. E.g. MgO + H2O ⇾ Mg(OH)2 That is why metallic oxides are said to be basic oxides. It turns red litmus paper blue. Secondly, metal oxides reacts with acids to form salt and water, which is a primary property of bases. |
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