Miscibility is the property of two substances to mix in all proportions, forming a homogeneous mixture. Such substances are said to be miscible. The term is most often applied to liquids but also applies to solids and gases. An example in liquids is the miscibility of water and ethanol as they mix in all proportions.
Diesel fuel is immiscible in water. The bright rainbow pattern is the result of thin-film interference.
In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration. The concentration can refer to any kind of chemical mixture, but most frequently refers to solutes and solvents in solutions. The molar (amount) concentration has variants, such as normal concentration and osmotic concentration. Dilution is reduction of concentration, e.g. by adding solvent to a solution. The verb to concentrate means to increase concentration, the opposite of dilute.
Test tubes with liquid in which a blue dye is dissolved in different concentrations. In the test tube with dark blue liquid (in front), the blue dye is dissolved in a high concentration. In the following test tubes, the blue dye is dissolved in a lower concentration (and at the same time in a smaller amount, since the volume is approximately the same). Image is AI generated.
These glasses containing red dye demonstrate qualitative changes in concentration. The solutions on the left are more dilute, compared to the more concentrated solutions on the right.
