Problem 15 - Chemistry: The Central Science

Question

A white substance melts with some decomposition at \(730^{\circ} \mathrm{C}\). As a solid, it does not conduct electricity, but it dissolves in water to form a conducting solution. Which type of solid (molecular, metallic, covalent- network, or ionic) might the substance be?

Step-by-Step Solution

Answer

The given white solid has a high melting point (730°C), does not conduct electricity as a solid, and dissolves in water to form a conducting solution. Based on these properties, it is most likely an ionic solid.

Step 1: Analyze the properties of each type of solid

Let's analyze the properties of molecular, metallic, covalent-network, and ionic solids. 1. Molecular solids: Low melting points, poor electrical conductivity, and typically dissolve in nonpolar solvents. 2. Metallic solids: High melting points, good electrical conductivity, and insoluble in most solvents. 3. Covalent-network solids: Very high melting points, poor electrical conductivity, and insoluble in most solvents. 4. Ionic solids: High melting points, poor electrical conductivity in the solid state, and they dissolve in water to form conducting solutions.

Step 2: Match the properties to determine the type of solid

The white solid has the following properties: - Melts at 730°C, indicating a relatively high melting point. - Doesn't conduct electricity as a solid. - Dissolves in water to form a conducting solution. Based on these properties, we can say the solid is most likely an ionic solid as its properties fit this type the best: - High melting points. - Poor electrical conductivity in the solid state. - They dissolve in water to form conducting solutions.