The scientific tool used to separate mixtures based on density is a centrifuge. A centrifuge spins samples at high speeds, generating centrifugal force that separates components according to their densities. Heavier particles move outward, while lighter ones remain closer to the center. This separation technique is widely used in laboratories for various applications, such as isolating cells, purifying proteins, and analyzing blood samples. The centrifuge is invaluable for research, diagnostics, and industrial processes.