WAEC SSCE - Chemistry - 1990 (Objective)

Question 1 Report

Which of the following statements explains why tetraoxosulphate (IV) acid is reqarded as a strong acid?

Tetraoxosulphate (IV) acid is dibasic

the acid is concentrated

the acid is complately ionized in aqueous solution

tetraxosulphate (IV) ions are very reactive

the acid is highly corrosive

Answer Details

The statement that explains why tetraoxosulphate (IV) acid is regarded as a strong acid is that the acid is completely ionized in aqueous solution. This means that when tetraoxosulphate (IV) acid dissolves in water, all the acid molecules dissociate into ions. In the case of tetraoxosulphate (IV) acid, the hydrogen ion (H+) and tetraoxosulphate (IV) ion (SO4²-) are formed when it dissolves in water. The completeness of ionization of a strong acid in aqueous solution is due to the stability of the resulting ions, which are highly charged and polar. This means that the ions are strongly attracted to the water molecules, making it difficult for them to recombine and reform the original acid molecule. As a result, the concentration of H+ ions in the solution is high, leading to a low pH value. In contrast, weak acids are only partially ionized in aqueous solution, meaning that only a fraction of the acid molecules dissociate into ions. This is due to the fact that the resulting ions are not as stable as those produced by strong acids. As a result, the concentration of H+ ions in a weak acid solution is lower, leading to a higher pH value. Therefore, tetraoxosulphate (IV) acid is regarded as a strong acid because it completely ionizes in aqueous solution, leading to a high concentration of H+ ions and a low pH value.

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)






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