The phrase “like dissolves like” explains that non-polar chemicals often dissolve other non-polar chemicals. Also, polar chemicals often dissolve polar chemicals. Because of its polar structure, water is often called the universal solvent.
The Correct Answer and Explanation is:
Correct Answer: Polar substances tend to dissolve other polar substances, and non-polar substances tend to dissolve other non-polar substances.
Explanation:
The phrase “like dissolves like” is a fundamental principle in chemistry that describes how substances dissolve in each other. It means that the solubility of a substance largely depends on its polarity. Polar substances have molecules with partial positive and partial negative charges due to unequal sharing of electrons. Non-polar substances, on the other hand, have molecules with an even distribution of electrons, so no partial charges exist.
When a solute (the substance being dissolved) and a solvent (the substance doing the dissolving) have similar polarities, they can interact effectively at the molecular level. For polar substances, this interaction often involves dipole-dipole attractions or hydrogen bonding. For example, ethanol (a polar molecule) dissolves well in water (also polar) because both can form hydrogen bonds.
In contrast, non-polar substances do not have regions of partial charge, so they cannot interact with polar molecules effectively. However, they can dissolve in other non-polar substances through London dispersion forces. For instance, oil (non-polar) can dissolve in gasoline (also non-polar), but not in water.
Water is a highly polar molecule due to the bent shape and the difference in electronegativity between hydrogen and oxygen atoms. Because of this polarity, water can dissolve many polar substances and ionic compounds by surrounding them and separating their particles. This ability to dissolve a wide variety of substances gives water the nickname “the universal solvent.”
Understanding solubility based on polarity is essential in various scientific and practical applications, such as in pharmaceuticals, cleaning, and environmental science. It explains why sugar dissolves in water but not in oil, or why some stains require non-polar solvents to remove. The rule “like dissolves like” provides a quick and useful guide to predict solubility behavior.
