Selected chlorides have the following melting points: \(\mathrm{NaCl}\) $\left(801^{\circ} \mathrm{C}\right), \mathrm{MgCl}_{2}\left(714^{\circ} \mathrm{C}\right), \mathrm{PCl}_{3}\left(-94^{\circ} \mathrm{C}\right), \mathrm{SCl}_{2}\left(-121^{\circ} \mathrm{C}\right)$ (a) For each compound, indicate what type its solid form is (molecular, metallic, ionic, or covalent-network). (b) Predict which of the following compounds has a higher melting point: \(\mathrm{CaCl}_{2}\) or \(\mathrm{SiCl}_{4}\).

To determine the type of solid for each compound, let's analyze their bonding characteristics and melting points: 1. \(\mathrm{NaCl}\): Sodium chloride has a high melting point (801°C) and is formed by the ionic bond between Na+ and Cl-. Thus, its solid form is ionic. 2. \(\mathrm{MgCl_2}\): Magnesium chloride also has a high melting point (714°C) and is formed by the ionic bond between Mg2+ and Cl-. Its solid form is also ionic. 3. \(\mathrm{PCl_3}\): Phosphorous trichloride has a low melting point (-94°C) and is formed by covalent bonds between P and Cl atoms. The solid form consists of discrete molecules, so its solid form is molecular. 4. \(\mathrm{SCl_2}\): Sulfur dichloride has a low melting point (-121°C) and is formed by covalent bonds between S and Cl atoms. Similar to PCl3, its solid form is molecular. Thus, the solid forms of the given chlorides are: - NaCl: Ionic - MgCl_2: Ionic - PCl_3: Molecular - SCl_2: Molecular

To predict which compound has a higher melting point between CaCl2 and SiCl4, let's analyze their bonding characteristics: 1. \(\mathrm{CaCl_2}\): Calcium chloride is formed by the ionic bond between Ca2+ and Cl-. Typically, ionic solids have higher melting points due to the strong electrostatic forces between ions. 2. \(\mathrm{SiCl_4}\): Silicon tetrachloride is formed by covalent bonds between Si and Cl atoms. The solid form of SiCl4 consists of discrete molecules, making its solid form molecular. Molecular solids generally have lower melting points due to weaker intermolecular forces. Based on this analysis, \(\mathrm{CaCl_2}\) (ionic solid) is predicted to have a higher melting point than \(\mathrm{SiCl_4}\) (molecular solid).