Which of the following metals is passive to concentrated trioxonitrate (V) acid?
Iron
Tin
Copper
Zinc
Explanation
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Video Explanation
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Discussions (17)
Aluminium and iron do not react with the conc acid probably due to the formation of a surface coating of oxide which is passive and stops any further action by the acid.Therefore,conc Hno3 is usually transported in containers lined with aluminium or iron.thanks
Aluminium
This link states that:-
Aluminium metal dissolves readily in dilute sulphuric acid to form solutions containing the aquated Al(III) ion togethe with hydrogen gas, . The corresponding reactions with dilute hydrochloric acid also give the aquated(III) ion. Concentrated nitric acid passivates aluminium metal (due to formation of thin protective oxide layer,
on surface of metal which cuts of further reaction. )
Lead
This link states that:-
The surface of metallic lead is protected by a thin layer of lead oxide, . This renders the lead essentially insoluble in sulphuric acid. Lead reacts slowly with hydrochloric acid and nitric acid. In the latter case, nitrogen oxides are formed together with lead(II) nitrate, .
Tin
This link states that:-
Tin is attacked only slowly by dilute acid such as hydrochloric acid and sulfuric acid. [...]Tin dissolves easily in concentrated acids.
Explanation:
Passivation occurs when a metal becomes coated with a thin, protective oxide layer that prevents further reaction with an acid.
Iron becomes passive in concentrated trioxonitrate(V) acid (HNO₃) due to the formation of a protective oxide layer on its surface. This layer stops further reaction between the metal and the acid.
Tin, copper, and zinc do not show passivation with concentrated HNO₃ in the same way; they either dissolve or react continuously.
Answer: A) iron
The answer is iron because iron forms an oxide when reacted with conc hno3 and stops any further reaction.
don't get confused guys rhe answer is zn because it forms a protective layer of zinc oxide (ZnO) on its surface, which acts as a barrier against further reaction with the acid. This protective layer prevents the acid from corroding the zinc metal.
