What factor causes lead oxide particles to settle faster than silica particles?

The settling velocity of particles in a fluid is significantly influenced by their density. Lead oxide particles generally have a higher density compared to silica particles. According to Stokes' Law, which describes the motion of spherical particles in a fluid, the settling velocity is directly proportional to the difference in density between the particle and the fluid in which it is suspended. Since denser particles are subject to a greater gravitational force relative to the buoyant force exerted by the fluid, they tend to settle more quickly.

In contrast, size, color, and shape also play roles in particle behavior, but they are less crucial than density when it comes to the rate of settling in this specific context. For instance, while larger particles may fall faster than smaller ones due to reduced drag, density remains the dominant factor when comparing particles like lead oxide and silica with significant differences in their respective weights. Thus, the higher density of lead oxide contributes to its faster settling rate compared to silica.