What occurs when you mix air with surfactant?

When air is mixed with surfactant, it primarily creates a foam. This is because surfactants are compounds that lower the surface tension between two liquids or between a liquid and a gas. When air is introduced into a liquid containing surfactants, the surfactant molecules arrange themselves at the air-liquid interface, significantly stabilizing the air bubbles that form.

Foam is essentially a stable dispersion of gas bubbles within a liquid. Surfactants help maintain the size and integrity of these bubbles, preventing them from merging and escaping, which is essential for creating sustained foam. This phenomenon is commonly observed in various applications, from household products like shaving cream and whipped toppings to industrial processes.

While mixing air and surfactant does not create a liquid, bubbles can form, but the term 'foam' specifically encompasses the larger structure created by the stabilization of those bubbles in the presence of surfactant. Increasing viscosity is not the main outcome of mixing air with surfactant; instead, it is more about the stabilization and formation of a foam structure.