Final answer:
Water is known as the "universal solvent" because it is a polar molecule that dissolves many substances like methanol and sodium sulfate, but not nonpolar substances like octane.
Step-by-step explanation:
The substance known as the "universal solvent" is water (H₂O). Water is considered a polar solvent, which means it has a partial negative charge on its oxygen atom and a partial positive charge on its hydrogen atoms. Thanks to this polarity, water can dissolve many substances through dipole-dipole interactions and ion-dipole interactions.
In the context of water being a polar solvent, the substances that should dissolve in water include:
- methanol (CH₃OH)
- sodium sulfate (Na₂SO₄)
However, substances like octane (C₈H₁₈), which are nonpolar, do not dissolve well in water. This is because nonpolar substances do not have regions of partial positive or negative charge that can interact with the polar water molecules.
Substances such as ethyl alcohol, methyl alcohol, ethylene glycol, and isopropyl alcohol can dissolve in water because they can engage in hydrogen bonding with water molecules. As the carbon chain length of alcohols increases, their solubility in water decreases due to the increasing nonpolar characteristics resembling hydrocarbons more than water.