why aluminium and zinc is acts as acid and base
Answers
Answer:
ZnO is an amphoteric oxide. In chemistry, an amphoteric compound is one that react as either an acid or a base. Many metals are amphoteric : copper, Zinc, Tin, lead, aluminum, and beryllium. According to the Bronsted –Lowrey theory of acids and bases, acids are proton donors (H3O+) and bases are proton acceptors (OH-).An amphoteric molecule or ion can either donate or accept a proton thus acting as either an acid or a base. Thus Zinc will dissolve in both acids and bases.
Aluminum has an electronegativity of 1.5. Exactly at the boundary where oxides of elements start becoming acidic. Oxides of elements of electronegativities below 1.5 readily give off their oxygens in water to grab water’s hydrogens forming hydroxide ions. This is because the bonding is often ionic hence the bond between the element and the oxygen breaks easily in water. However, beyond 1.5, the element will hold on to the oxygen more strongly and will instead form acids by covalently bonding with more oxygens to form acid anions. The negative charge is going to exist in the oxygen atoms. Al2O3, being exactly 1.5, is equally likely to give off or grab oxygens because of the de-facto covalent/ionic nature of its bonds. In acidic conditions, protons in the solution will protonate the oxygen forming water and Al’s corresponding salt. In certain basic coditions however, hydroxide ions promote the formation of more hydroxide ions from Al’s oxygens forming a hydrated aluminate complex and water. The reaction here is way more complicated than a regular acid-base reaction.
This is the simplest, most easily understandable explanation I can give you
Explanation:
Answer:
Explanation:
Because aluminium hydroxide is amphoteric in nature. Amphoteric oxides have the property that they can both act as a base and acid.
From wikipedia:
In acid, it acts as a Brønsted-Lowry base by picking up hydrogen ions and neutralizes the acid, yielding a salt:
3HCl + Al(OH)3→ AlCl3+ 3H2O
In bases, it acts a Lewis acid by taking an electron pair from the hydroxide ions:
Al(OH)3+ OH–→ Al(OH)4–
( - represents negative)