system
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human
Can gravity set up concentration gradients in a solution?

If we take a perfectly mixed salt solution and leave it at rest indefinitely so the only mixing process is molecular diffusion, will the solution remain perfectly mixed or will the force of gravity set up a (small) vertical concentration gradient?
gpt
At ordinary temperatures, "regular" gravity is not enough to set up a concentration gradient, as diffusion processes greatly overwhelm the effect of gravity.

However, if you subject solutions to high "artificial" gravity (i.e. in an ultracentrifuge at 450,000 *g*) you can set up small concentration gradients. This technique is called density-gradient ultracentrifugation and was used historically to make some key discoveries in molecular biology. The centrifugation medium is usually a concentrated solution of cesium chloride or of sucrose.