Question

Among $A{l}_2{O}_3,Si{O}_2,P_2{O}_3,andS{O}_3$ , the correct order of acid strength is:

• A. Al₂O₃ < SiO₂ < SO₃ <P₂O₃
• B. SiO₂ < SO₃ < Al₂O₃ < P₂O₃
• C. SO₃ < P₂O₃ < SiO₂ < Al₂O₃
• D. Al₂O₃ < SiO₂ < P₂O₃ < SO₃

Answer 1

The correct option is D

Al₂O₃ < SiO₂ < P₂O₃ < SO₃

In general, the electropositive character of the oxide's central atom will determine whether the oxide will be acidic or basic. The more electropositive the central atom, the more basic the oxide. The more electronegative the central atom, the more acidic the oxide. Electropositive character increases from right to left across the periodic table and increases down the column. The trend of acid-base behaviour is from strongly basic oxides on the left-hand side to strongly acidic ones on the right, via an amphoteric oxide (aluminium oxide) in the middle.

Therefore, $A{l}_2{O}_3<Si{O}_2<P_2{O}_3<S{O}_3$