Miscible

Summary: Two liquids are miscible if they mix completely in all proportions to form a homogeneous solution (e.g., ethanol and water). Immiscible liquids do not mix and form separate layers (e.g., oil and water). Tags: igcse chemistry liquids keyword Created: 2026-07-14 Last Updated: 2026-07-14

Miscible describes two liquids that dissolve in one another in all proportions to form a single, homogeneous layer, with no visible boundary between them — ethanol and water are the most commonly cited miscible pair in IGCSE chemistry. The miscibility of two liquids depends on their molecular polarity: “like dissolves like” — polar solvents such as water mix readily with other polar liquids (e.g., ethanol, propanone) because the intermolecular forces (hydrogen bonds, dipole-dipole attractions) between the different molecules are comparable in strength to those within each pure liquid. Immiscible liquids, by contrast, do not mix and form two distinct layers, as seen with oil and water, because the non-polar oil molecules cannot form favourable interactions with the highly polar water molecules. The practical importance of miscibility lies in separation technique selection: miscible liquids with different boiling points are separated by fractional distillation (exploiting boiling point differences), whereas immiscible liquids are separated using a separating funnel, simply by draining the denser lower layer and collecting the upper layer separately. IGCSE candidates should be prepared to identify whether fractional distillation or a separating funnel is the appropriate apparatus based solely on whether two liquids are described as miscible or immiscible.

Key term — IGCSE Chemistry (0620/0971) glossary.