Why isn't settling always used to separate particles suspended in a liquid?

Answer 1

because sometimes the particles are too small to settle out. that's why scientists came up with alternate techniques

Answer 2

The reason scientists use other techniques has nothing to do with the weight or size, but rather the density of the particle involved. An example of why the previous assumptions are wrong: A log floats on water. It is both heavy and large. The simple fact that wood is less dense than water (.7g/cm^3 compared to 1.0g/cm^3) tells us that it will float.

Scientists often use centrifugation (spinning it in circles very fast) to settle out particles. This is much quicker as well. Settling often takes hours, but centrifugation finishes the job in a matter of minutes.

Answer 3

sometime particals may float on the surface of water due to lighter in weight and sometime it forms suspetion with liquid and this is difficult to seperate by simple settling. Particles separation by settling method can be used for heavy impurities which can be easily settled down and can be seperated.

Answer 4

hi..
settling is a method used when the stuff suspended in water is big enough.. wat i mean is, wen the individual grains hav a larger diameter.. like sand grains ( of course, th dia is in the order of micrometer or lesser)..
but for smaller, or rather finer particles, this method cannot b used de dont settle down.. des particles are the order of nanometers or lesser..
so other techniques hav 2 b used.