Explain the following:
(a) Sodium chloride is an ionic compound which does not conduct electricity in solid state where as it does conduct electricity in molten state as well as in aqueous solution.
(b) Reactivity of aluminium decrease if it is dipped in nitric acid.
(c) Metals like calcium and magnesium are never found in their free state in nature.
Answers
Answer:
sodium chloride (NaCl) cannot conduct electricity in it's solid form because it doesn't contain H+ ion which helps to begin the flow of current. so when we put H2O or water it becomes aqueous as well as it gains H+ ions from water which helps to conduct electricity
a) Sodium chloride is an ionic compound which does not conduct electricity in solid state as it does in the aqueous solution because -
• The sodium chloride doesn't have any free electrons in it's solid state and that's why it cannot conduct electricity in the solid state.
• On the other hand,the sodium chloride gets ionised (Na+ & Cl-) in the aqueous solution,and these ions conduct electricity.
b) Reactivity of aluminium decrease if it is dipped in nitric acid because-
• A thin layer of aluminium oxide is formed when the aluminium metal reacts with the diluted nitric acid.
• This layer of non-reactive aluminium oxide decreases the allover reactivity of the aluminium metal.
c) Metals like calcium and magnesium are never found in their free state in nature because -
• These metals are highly reactive and can bond easily with the other elements present in the environment without any excessive efforts.