Chapter U1.22, Problem 7E

Interpretation Introduction

Interpretation:

The option that does not represent the possible compound with sulfate ion should be predicted.

Concept introduction:

Ion that is covalently bonded with the two or more atoms and considered as a single unit and also has net charge on it, is known as polyatomic ions.

Answer to Problem 7E

The correct option is (b).

Explanation of Solution

The ${\text{SO}}_{\text{4}}{}^{2-}$ is a polyatomic ion. The charge on it is -2. The possible compound with sulfate would satisfy the charge on each ion.

Explanation for correct answer:

(b) The given compound is ${\text{KSO}}_{\text{4}}$. The charge on K is + 1, two K ions are required to bonded with ${\text{SO}}_{\text{4}}{}^{2-}$. Thus, the chemical formula is incorrect and it would be ${\text{K}}_2{\text{SO}}_{\text{4}}$. Therefore, the option (b) is correct.

Conclusion

Explanation for incorrect answer:

(a) The given compound is ${\text{Na}}_2{\text{SO}}_{\text{4}}$. The charge on Na is + 1, two Na ions are required to bonded with ${\text{SO}}_{\text{4}}{}^{2-}$. Thus, the chemical formula is correct. Therefore, the option (a) is incorrect.

(c) The given compound is ${\text{Al}}_2{\left({\text{SO}}_{\text{4}}\right)}_3$. The charge on Al is + 3, two Al ions are required to bonded with three ${\text{SO}}_{\text{4}}{}^{2-}$. Thus, the chemical formula is correct. Therefore, the option (c) is incorrect.

(d) The given compound is ${\text{CaSO}}_{\text{4}}$. The charge on Ca is + 2, one Ca ion is required to bonded with ${\text{SO}}_{\text{4}}{}^{2-}$. Thus, the chemical formula is correct. Therefore, the option (d) is incorrect.