Aluminimumdissolvesin mineralacids and aqueousalkalies and thus showsamphotericcharacter place ofaluminiumfoil istreatedwith dilutehydrochloricacid or dilutesodium hydroxide solutiona test tube andon bringing a burning matchstick near the monthof thetest tube , a pop southindicatesthe evolutionof hydrogengas. Thesame activitywhenperformedwith concentratednitrogen acid, reaction doesn'tproceed. Explain the reason.

Aluminimumdissolvesin mineralacids and aqueousalkalies and thus showsa

1.	Aluminimumdissolvesin mineralacids and aqueousalkalies and thus showsamphotericcharacter place ofaluminiumfoil istreatedwith dilutehydrochloricacid or dilutesodium hydroxide solutiona test tube andon bringing a burning matchstick near the monthof thetest tube , a pop southindicatesthe evolutionof hydrogengas. Thesame activitywhenperformedwith concentratednitrogen acid, reaction doesn'tproceed. Explain the reason.
Answer» Solution :Al being amphoteric dissolvesboth in acidsand alkalies evolving`H_(2)` gas whichburnswith a popsouth `2Al + 6HCl rarr AlCl_(3) + 3H_(2)` `2Al + 2NaOH + 2H_(2)O rarr underset(" Sod. Meta-aluminate ")(2 NaAlO_(2)) +3H_(2)` With CONC. `HNO_(3)`, Al becomespassive and the reactiondoes not proceed.This passiveis DUE to fromationof a thinpratectivelayer of its oxide `(Al_(2)O_(3))` on the surfaceof themetalwhich preventsfurther ACTION. `2Al + 6HNO_(3) rarr Al_(2)O_(3) + 6NO_(2) + 3H_(2)O`.