Chapter 8, Problem 132A

Interpretation Introduction

Interpretation:

The two covalent compounds arsenic (III) oxide and diarsenic trioxide is to be compared and contrasted.

Concept introduction:

In the molecular formula, the element symbols and the subscripts number tells the type and the number of each atom in a molecule.

There are so many methods to represent a molecule. In ball-and-stick method, the atoms of each element are depicted by ball and the bond is depicted by stick. In structural formula method, the atoms of each element are depicted by letter symbols and bond is used to show relative position.

Answer to Problem 132A

The molecular formula of both covalent compounds arsenic (III) oxide and diarsenic trioxide is same ${\text{As}}_{\text{2}}{\text{O}}_{\text{3}}$ even though they are named differently.

Explanation of Solution

In first covalent compound, arsenic (III) oxide, roman III represents the oxidation number of arsenic. Therefore, arsenic has oxidation number of +3. It is known that oxide has oxidation number of -2. To get neutral compound, 2:3 ratio of arsenic and oxygen is required. Therefore, the molecular formula of arsenic (III) oxide is ${\text{As}}_{\text{2}}{\text{O}}_{\text{3}}$.

The second covalent compound, diarsenic trioxide, indicates that there are two atoms of arsenic and three atoms of oxygen. Therefore, the molecular formula of diarsenic trioxide is ${\text{As}}_{\text{2}}{\text{O}}_{\text{3}}$.

Therefore, both covalent compounds arsenic (III) oxide and diarsenic trioxide are named differently even though both have same molecular formula.

Conclusion

The molecular formula of both covalent compounds arsenic (III) oxide and diarsenic trioxide is same ${\text{As}}_{\text{2}}{\text{O}}_{\text{3}}$ even though they are named differently.