why must we used sulfuric acid H2SO4, in 2KAl(OH)4 + H2SO4->2Al(OH)3(s)+K2SO4 +2H2O and 2Al(OH)(s)+3H2SO4->Al2(SO4)3+6H2O rather than hydrochloric acid,HCl,or nitric acid, HNO3?

Your question is a little confusing because of lack of information. If you are trying to make Al2(SO4)3 you must use H2SO4. HCl would produce the chloride and HNO3 would produce he nitrate.

In the chemical reactions you mentioned involving potassium aluminum hydroxide (KAl(OH)4) and aluminum hydroxide (Al(OH)3), sulfuric acid (H2SO4) is used instead of hydrochloric acid (HCl) or nitric acid (HNO3) for specific reasons.

1. Reaction with KAl(OH)4:
The reaction between KAl(OH)4 and H2SO4 produces aluminum hydroxide (Al(OH)3), potassium sulfate (K2SO4), and water (H2O). The reason sulfuric acid is used in this reaction instead of HCl or HNO3 is due to the reactivity and availability of the acids. Sulfuric acid is a strong acid and serves as a good source of hydrogen ions (H+), which are required for the reaction to occur. Additionally, sulfuric acid is relatively inexpensive and widely available in comparison to HCl or HNO3.

HCl and HNO3 are also acids, but they have different properties and reactivities. HCl is a strong acid, similar to H2SO4, but it can react with aluminum hydroxide to form aluminum chloride (AlCl3), which is not the desired product in this reaction. On the other hand, HNO3 is a strong acid and can dissolve aluminum hydroxide, making it unfavorable for the formation of Al(OH)3.

2. Reaction with Al(OH)3:
The second reaction involves the reaction between Al(OH)3 and H2SO4 to produce aluminum sulfate (Al2(SO4)3) and water (H2O). Again, sulfuric acid is used because it provides the necessary hydrogen ions for the reaction, promoting the formation of the desired product.

HCl is not suitable for this reaction because it would generate aluminum chloride (AlCl3), which is not the desired product. Similarly, HNO3 is not preferred as it can dissolve the aluminum hydroxide rather than reacting with it to form Al2(SO4)3.

Therefore, the choice of sulfuric acid (H2SO4) in these reactions is based on its reactivity, availability, and compatibility with the desired products.