Clouds are made up of tiny water droplets or ice crystals floating in the air. Based on what you know about solutions, suspensions and colloids, what type of mixture do you think clouds are and why?
Clouds are a type of colloid. This is because clouds consist of tiny water droplets or ice crystals floating in the air, which matches the structure of a colloid where a dispersed phase (water droplets or ice crystals) is suspended in a dispersion medium (air).
Unlike a suspension, the particles in clouds do not settle down easily over time; they remain uniformly dispersed throughout the air, just like the particles in a colloid. Furthermore, clouds scatter light, showing the Tyndall effect, which is a defining property of colloids but not of transparent solutions.
Explanation
The textbook explains that colloids differ from solutions and suspensions based on particle size (1–1000 nm for colloids). A key property of colloids is that their particles do not settle over time and are uniformly dispersed. Additionally, colloids scatter light, known as the Tyndall effect. Clouds fit this description perfectly: the tiny water droplets or ice crystals act as the dispersed phase in the air (dispersion medium), they float without settling quickly, and they scatter sunlight, making them visible. Thus, clouds are classified as colloids.