Question

Which of the following happens when solid sodium chloride dissolves in water?A.The attractive forces between water and the sodium and chloride ions are overcome by the attractive forces between the sodium and chloride ions.B.The positive side of water's dipole moment is attracted to the sodium ions.C.The negative side of water's dipole moment is attracted to the chloride ions.D.The attractive forces between the sodium and chloride ions are overcome by the attractive forces between the water and the sodium and chloride ions.

Answer 1

Answer: option D. The attractive forces between the sodium and chloride ions are overcome by the attractive forces between the water and the sodium and chloride ions.

Explanation:

Solid sodium chloride (NaCl) is a ionic compound formed by ionic bonds between by the positive, metallic cations of sodium atom, Na⁺, and the negative, non-meatllic anions of chlorine atom, Cl⁻ (chloride).

Ionic bonds, then, are the electrostatic attracion between oppositely charged particles (cations and anions).

When solid sodium chloride dissolves in water, the ions (cations and anions) are separated in the solvent (water) due to the superior attracitve forces between such ions and the polar water molecules.

Water (H₂O) is a molecule, formed by polar covalent bonds between two hydrogen atoms and one oxygen atom.

The polarity of water molecule is due to the fact that oxygen atoms are more electronegative than hydrogen atoms, which cause that the electron density is closer to oxygen nuclei than to hydrogen nuclei. This asymmetry in the electron density conferes a partial positive charge over each hydrogen atom and a partial negative charge over the oxygen atoms.

Thus, the positively charged hydrogen atoms attract and surround the negative chloride (Cl⁻) anions, while the negatively charged oxygen atoms attract and surround the positive sodium (Na⁺) cations. It is only because the attractive forces between the water and the sodium and chloride ions are stronger than the attractive forces between the sodiium and chloride ions that such ions may be kept separated in the solution. This process is called solvation and the ions are said to be solvated by the water molecules.