Question

which of the following best represents how a polar covalent compound is dissolved in water?

Explanation:

Step1: Recall Dissolution of Polar Compounds

Polar covalent compounds dissolve in water (a polar solvent) via dipole - dipole interactions. Water molecules (\(H_2O\)) are polar, with the oxygen end being partially negative (\(\delta^-\)) and the hydrogen end being partially positive (\(\delta^+\)). A polar covalent compound also has partial positive and partial negative regions. When dissolving, water molecules surround the polar compound: the negative part of water (O) is attracted to the positive part of the polar compound, and the positive part of water (H) is attracted to the negative part of the polar compound.

Step2: Analyze the Diagrams

• The first diagram (with the blue oval having a + sign and red - white (representing \(H_2O\)) molecules around it) shows water molecules (red - white) surrounding the polar compound (blue oval with +). The orientation of water molecules (O near the + of the compound, H near the - of the compound, though not shown for the compound's - here, but the arrangement of water molecules around the polar species is consistent with dipole - dipole interactions in dissolution.
• The other diagrams: The ones with just + and - ions or non - polar - like arrangements do not represent the dissolution of a polar covalent compound (polar covalent compounds do not dissociate into ions like ionic compounds, so the diagrams with separate + and - ions are for ionic compound dissolution). The diagrams with just water molecules or non - interacting species also do not show the solvation of a polar covalent compound.

Answer:

The first diagram (the one with the blue oval with a + sign and red - white water - like molecules surrounding it)