Mole (unit) measure the amount of substance (although in practice it is usual). There are many physical relationships between amount of substance and other physical quantities, the most notable one being the ideal gas law (where the relationship was first demonstrated in 1857). The term "mole" was first used in a textbook describing these colligative properties. Chemical engineers use the unit extensively, and decimal multiples may be more suitable for industrial use. For convenience in avoiding conversions in the imperial (or American customary units), some engineers adopted the "pound-mole" (notation "lb-mol" or "lbmol"), which is defined as the number of entities in
Bubble (physics) Bubble (physics) A bubble is a globule of one substance in another, usually gas in a liquid. Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance. Bubbles are seen in many places in everyday life, for example: Bubbles form, and coalesce, into globular shapes, because those shapes are at a lower energy state. For the physics and chemistry behind it, see nucleation. Bubbles are visible because they have a different refractive index (RI) than the surrounding substance. For example, the RI of air is approximately 1.0003 and the RI of water