Chemistry Liquids NUMS 2022
PMDC Verified Question 48 of 73
Which of the following statement explains solubility of ionic substance in water?
A
Water molar mass is 18.02
B
Water molecule is polar
C
Water forms dative bonding
D
Water has high density
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Water molecule is polar
Concept:

The principle of "like dissolves like" dictates that ionic and polar substances dissolve best in polar solvents.

Formula:

Not applicable.

Solution:

  • Ionic solids are held together by massive electrostatic lattice energies.


  • Water (\( \text{H}_2\text{O} \)) is highly polar. Its Oxygen end carries a partial negative charge, and its Hydrogen ends carry partial positive charges.


  • When an ionic compound is introduced, the polar water molecules surround and attack the crystal lattice. The negative oxygen ends pull away positive cations, and the positive hydrogen ends pull away negative anions (Ion-Dipole forces), successfully dissolving the solid.


Why other options are incorrect:

Molar mass and density are irrelevant to the electrostatic solvation process. While water can occasionally act as a ligand in transition metal complexes, its general macroscopic ability to dissolve salts is entirely due to its polarity.

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