Solid sodium chloride is added to liquid water and fully dissociates to produce an…
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
Solid sodium chloride is added to liquid water and fully dissociates to produce an aqueous solution containing Na⁺ and Cl⁻ ions. The particulate-level drawing that will appear in an assessment must correctly depict the orientation of surrounding water molecules around each type of ion.
(a) Identify the partial charges on the oxygen and hydrogen atoms in a water molecule, and state how those partial charges are typically indicated in particulate-level diagrams.
(b) Describe in words how at least three water molecules in the first solvation shell should be oriented with respect to a single Na⁺ ion. Your description must specify which end of each water molecule points toward the ion and why.
(c) Describe in words how at least three water molecules in the first solvation shell should be oriented with respect to a single Cl⁻ ion, again specifying which end of each water molecule points toward the ion and why.
(d) Using Coulombic considerations, explain why the orientations you described in parts (b) and (c) are different even though the solvent is the same.