Question

You are given a white substance that sublimes at \(3000^{\circ} \mathrm{C}\); the solid is a nonconductor of electricity and is insoluble in water. Which type of solid (molecular, metallic, covalent-network, or ionic) might this substance be?

Short answer

Considering that the substance sublimes at \(3000^{\circ} \mathrm{C}\), is a nonconductor of electricity, and is insoluble in water, it can be concluded that this white substance might be either a molecular or a covalent-network solid. Further information would be needed to definitively identify the specific type.

Step-by-step solution

Analyzing the properties

We'll begin by analyzing the given properties: 1. Sublimation at 3000°C: The substance directly turns from solid to gas phase upon heating to 3000°C. Sublimation is a process commonly found in molecular and covalent-network solids, as no intermediate liquid phase is formed. 2. Non-conductor of electricity: The given substance does not allow the flow of electricity. This indicates that there are no free electrons or charged ions, which narrows our possibilities down to molecular or covalent-network solids. 3. Insoluble in water: The substance does not dissolve in water, which suggests that the substance does not form any favorable interactions with water molecules such as hydrogen bonds or ion-dipole interactions. Ionic solids would typically dissolve in water, so we can further eliminate the ionic type.

Concluding the type of solid

Based on the properties we've analyzed, we can reach the conclusion that the given white substance could be either a molecular or a covalent-network solid as both exhibit the qualitative properties described in the exercise: high sublimation temperature, non-conductivity, and insolubility in water. Without further information or a specific chemical formula for the substance, it is difficult to definitively identify the substance as either a molecular or a covalent-network solid. But using the given information, we can confidently say that it might be either a molecular solid or a covalent-network solid.

Key concepts

Sublimation

Sublimation is an intriguing process where a substance transitions directly from a solid state to a gas, bypassing the liquid state entirely. Consider it like dry ice disappearing into a fog without ever becoming wet. This happens because, at a given temperature and pressure, the energy of the particles in the solid becomes high enough to leap straight into the gaseous phase.

Materials that sublime do so at particular conditions. For a substance to sublimate at an incredibly high temperature like 3000°C indicates strong intermolecular forces maintaining the solid structure until extreme heat allows escape as vapor. Sublimation typically occurs in substances such as covalent-network solids that have significant bond interactions. This property makes them resistant to melting under increased heat, unlike some molecular solids which may sublime too but generally at lower temperatures.

Non-conductor of Electricity

A non-conductor of electricity is a material that does not easily allow electric current to pass through it. In simple terms, it doesn't let electricity flow, analogous to a solid wall stopping water. The reason behind this lies in the absence of free electrons or charged particles that can move under an electric field.

While metals are good conductors due to their sea of free electrons, covalent-network solids lack this feature. Instead, electrons are tightly held within covalent bonds, providing no mobility for charge transport. As a result, these materials are excellent insulators. Understanding the non-conductive nature helps differentiate solid types: ionic solids, molecular solids depending on the region and form, and metals can conduct electricity under certain conditions, whereas covalent-network solids generally cannot.

Insolubility in Water

Insolubility in water means that a substance does not dissolve or break apart in water. This happens because there are no interactions or attractions strong enough between the substance's molecules and water molecules to overcome the bonding force holding the solid together.

Covalent-network solids, like diamonds or quartz, are typically insoluble because of their strong covalent bonds throughout the structure. These bonds create a rigid, stable framework that water is unable to penetrate or disrupt. Ionic substances often dissolve because water can stabilize the free ions; however, covalent-network and some molecular solids lack this trait.

• Highly bonded structure is resistant to water.
• Lack of ion formation which contributes to solubility.
• Brings comprehension about solid state features more relatable in behavior and interaction with the environment.

Recognizing these can guide one in predicting and understanding the behavior of unknown solids like the one from the exercise.