Which pair is miscible?

Which pair is miscible?

• A. Oil and Water
• B. Sand and Water
• C. Water and Ethanol
• D. Honey and Water

Answer: (C)

Two liquids are miscible when they mix in all proportions to form a single, homogeneous phase. Water and ethanol are the classic example because ethanol is a polar molecule that can form hydrogen bonds with water. The forces between water–water and water–ethanol, and between ethanol–ethanol, mix cooperatively and there’s no tendency for the liquids to separate into layers. That means you can combine any amount of water with any amount of ethanol and still get one uniform liquid. In contrast, oil and water don’t mix well because oil is nonpolar while water is highly polar; mixing would disrupt strong water–water hydrogen bonding and isn’t energetically favorable, so they separate into two layers. Sand and water don’t form a true solution either—the sand is a solid and won’t dissolve, so it remains as a suspension rather than a single liquid phase. Honey and water can mix as well, since honey is already mostly water with dissolved sugars, forming a uniform solution, but the most straightforward, complete miscibility across all proportions is clearly demonstrated by water and ethanol.

Two liquids are miscible when they mix in all proportions to form a single, homogeneous phase. Water and ethanol are the classic example because ethanol is a polar molecule that can form hydrogen bonds with water. The forces between water–water and water–ethanol, and between ethanol–ethanol, mix cooperatively and there’s no tendency for the liquids to separate into layers. That means you can combine any amount of water with any amount of ethanol and still get one uniform liquid.

In contrast, oil and water don’t mix well because oil is nonpolar while water is highly polar; mixing would disrupt strong water–water hydrogen bonding and isn’t energetically favorable, so they separate into two layers. Sand and water don’t form a true solution either—the sand is a solid and won’t dissolve, so it remains as a suspension rather than a single liquid phase. Honey and water can mix as well, since honey is already mostly water with dissolved sugars, forming a uniform solution, but the most straightforward, complete miscibility across all proportions is clearly demonstrated by water and ethanol.