Water is often called the “universal solvent” because many substances can be dissolved in water. What property of water allows it to be such a versatile solvent? a) The positive and negative charges on water molecules form strong attractions toward ions and other charged particles. b) The neutral pH of pure water means there are no other molecules to interfere with the dissolving process. c) The high specific heat capacity of water allows it to absorb large amounts of solutes with very little energy needed. d) The low density of liquid water means there is room for solutes to fit in between the water molecules.
The Correct Answer and Explanation is:
Correct Answer:
a) The positive and negative charges on water molecules form strong attractions toward ions and other charged particles.
Explanation:
Water is considered a universal solvent primarily due to its polarity. A water molecule has a bent shape where the oxygen atom carries a slight negative charge, and the hydrogen atoms carry slight positive charges. This separation of charge creates a polar molecule. When ionic or polar compounds are introduced to water, the positive end of the water molecule is attracted to negatively charged ions or molecules, and the negative end is attracted to positively charged ones.
This strong electrostatic attraction between water molecules and other charged particles enables water to surround and separate them. For example, when salt (sodium chloride) dissolves in water, the positive sodium ions (Na⁺) are attracted to the negative oxygen side of water molecules, and the negative chloride ions (Cl⁻) are attracted to the positive hydrogen side. Water molecules surround each ion, pulling them apart from the crystal structure and dispersing them evenly throughout the solution.
The other choices are incorrect for the following reasons:
- b) Although pure water has a neutral pH, that does not influence its ability to dissolve substances. Neutral pH means equal concentrations of hydrogen and hydroxide ions, not the absence of molecules.
- c) Specific heat capacity relates to how much energy is needed to change the temperature of a substance, not its dissolving ability.
- d) Water is not particularly low in density compared to other liquids, and solubility is not determined by available space between molecules.
Therefore, it is the polarity and resulting electrostatic interactions that make water such an effective and versatile solvent.
