Question

Compare and contrast the two covalent compounds identified by the names arsenic(III) oxide and diarsenic trioxide.

Short answer

Both arsenic(III) oxide and diarsenic trioxide have the same molecular formula, As2O3, which indicates they are the same covalent compound with different names. They share a similar structure, where arsenic and oxygen atoms are covalently bonded, as well as similar properties, like being white crystalline solids and having a molecular weight of 197.84 g/mol. Thus, there are no significant differences between these two compounds.

Step-by-step solution

Identify the molecular formulas of the compounds

Based on the names, determine the molecular formulas of arsenic(III) oxide and diarsenic trioxide. Arsenic(III) oxide refers to a compound containing arsenic ions with a charge of +3 valence electrons, combined with oxygen ions (which have a charge of - 2 valence electrons). Thus, the molecular formula for arsenic(III) oxide is As2O3. Diarsenic trioxide refers to a compound containing two arsenic atoms and three oxygen atoms. Thus, the molecular formula for diarsenic trioxide is also As2O3.

Investigate the structure and properties of the compounds

Since both compounds have a molecular formula of As2O3 and belong to the category of covalent compounds, they have a similar structure and properties. Both compounds consist of a layer structure, where arsenic and oxygen atoms are covalently bonded. As2O3 forms a polymeric structure where the arsenic atom is bonded to four oxygen atoms.

Compare and contrast the compounds

When comparing and contrasting the two compounds, we find that they are, in fact, the same substance described with two different names. Both arsenic(III) oxide and diarsenic trioxide have the same molecular formula (As2O3) and have the same covalent bonding structure. They also share similar properties, like being white crystalline solids, having a molecular weight of 197.84 g/mol, and subliming directly from solid to gas form at a temperature of 465 degrees Celsius (865°F). In conclusion, arsenic(III) oxide and diarsenic trioxide are merely two different names for the same covalent compound, As2O3.

Key concepts

Molecular Formula

The molecular formula is a way of expressing the quantity and type of each atom present in a molecular compound. Unlike simple empirical formulas, which only show the smallest whole number ratio of atoms in a compound, molecular formulas specify the exact number of each atom in a molecule, giving scientists and students a clear picture of the compound's composition.

For example, the molecular formula of arsenic(III) oxide is As₂O₃, which tells us that there are two arsenic atoms and three oxygen atoms. Despite potentially different names or synonyms, the molecular formula remains a definitive identifier for a compound. It's crucial when determining the compound's molar mass or when balancing chemical equations. As in our exercise, both arsenic(III) oxide and diarsenic trioxide share the molecular formula As₂O₃, indicating that they are indeed the same substance.

Chemical Nomenclature

Chemical nomenclature is the system used for naming chemical substances, allowing chemists to convey precise information about the chemical composition of a compound. There are various nomenclature systems, but the most widely accepted is the IUPAC (International Union of Pure and Applied Chemistry) system.

In the IUPAC system, compounds are named based on their elements and the number of atoms present. The name arsenic(III) oxide indicates that the arsenic has a valency of three, pairing with oxygen to form a compound. On the other hand, the name diarsenic trioxide tells us directly that there are two arsenic atoms and three oxygen atoms.

This can sometimes lead to confusion when a single substance, like As₂O₃, has multiple names. Educating students on both systematic and common names not only helps in better understanding academic exercises but is also essential for communication in the field of chemistry.

Compound Properties

Compound properties are the physical and chemical characteristics that define a substance and determine its behavior under different conditions. They include attributes like state of matter, color, melting and boiling points, solubility, toxicity, and reactivity.

For instance, both arsenic(III) oxide and diarsenic trioxide are white crystalline solids, have a molecular weight of 197.84 g/mol, and sublime at the temperature of 465 degrees Celsius. Knowing the properties of covalent compounds like As₂O₃ is crucial for understanding how they will interact with other substances and for their safe handling and storage.

It's also important to consider that while some properties can be determined solely by the molecular formula, others are influenced by the structural arrangement of the atoms, hence studying both molecular and structural formulas as well as the actual arrangement of atoms within the molecule is fundamental to grasp the full range of compound properties.