Some examples of miscible solutions include water and organic compounds such as alcohols, aldehydes and ketones. Immiscible solutions include water and many types of oils. A miscible solution is any solution that can be mixed together to form one liquid phase. Immiscible solutions do not mix together and instead form separate layers.
Many liquids fall somewhere in between miscible and immiscible. When this occurs, they are often referred to as partially miscible. When these liquids are mixed together, there are two distinct layers, but each layer contains some of the other. For instance, when water and some organic acids are mixed, two layers remain, but the layer with water contains some acid and the layer with acid contains some water. When liquids are immiscible, they are separated by a thin layer between them known as the meniscus. Separation of immiscible liquids can be accomplished with a separation funnel. One liquid is collected first, then the other in a separate container.
Miscibility is usually used to describe liquids, but it can also be used to refer to solids and gases. Metals are examples of items that are either miscible or immiscible as solids and liquids. Immiscible metals cannot form alloys. Copper and cobalt are immiscible metals in the solid state. In the liquid state, silver is miscible in zinc, but liquid zinc and liquid silver are immiscible in lead.