Which of the following properties of water explains its solvent abilities for certain substances?
A.
Polarity of water molecules
B.
High specific heat
C.
High surface tension
D.
Kinetic energy of liquid water molecules
The Correct answer and Explanation is:
The correct answer is A. Polarity of water molecules.
Explanation:
Water is often referred to as the “universal solvent,” a property largely attributed to its molecular structure and polarity. Each water molecule (H₂O) consists of one oxygen atom covalently bonded to two hydrogen atoms. The oxygen atom is more electronegative than hydrogen, leading to a significant difference in charge distribution across the molecule. This results in a partial negative charge near the oxygen and partial positive charges near the hydrogens, creating a polar molecule.
The polarity of water allows it to interact with various substances, especially ionic compounds and polar molecules. When an ionic compound, such as sodium chloride (NaCl), is placed in water, the positive part of the water molecules (the hydrogen side) is attracted to the negatively charged chloride ions, while the negative part (the oxygen side) is attracted to the positively charged sodium ions. This interaction effectively pulls the ions apart and disperses them throughout the solution, which is why salt dissolves in water.
Additionally, polar substances, such as sugars and alcohols, also dissolve well in water due to similar attractions between the polar regions of water molecules and the functional groups of these solutes. This solvation process stabilizes the dissolved molecules or ions, allowing them to remain in solution.
In contrast, non-polar substances, like oils or fats, do not dissolve in water because there is little to no attraction between the non-polar molecules and water’s polar molecules. As a result, the unique polar characteristics of water not only make it an excellent solvent but also play a critical role in biological processes, such as nutrient transport, cellular function, and metabolic reactions. Understanding water’s polarity is fundamental to appreciating its vital role in chemistry and biology.