How does centrifugation separate mixtures based on density?

Centrifugation separates mixtures based on density by spinning them rapidly, causing denser components to move outwards.

Centrifugation is a process that utilises the principle of sedimentation, where the centripetal acceleration causes denser substances to separate out along the radial direction (the bottom of the tube). By spinning the mixture at high speed, the components of the mixture are subjected to different forces due to their different densities, which leads to their separation.

Imagine a mixture of oil and water. When this mixture is placed in a centrifuge and spun at high speed, the denser water molecules are forced to the bottom of the tube, while the less dense oil molecules remain at the top. This is because the denser a substance is, the greater the force it experiences in a centrifuge.

The same principle applies to more complex mixtures. For example, in a blood sample, the red and white blood cells are denser than the plasma. When the blood sample is centrifuged, the cells move to the bottom of the tube, while the plasma stays at the top.

It's important to note that the speed and duration of centrifugation can affect the separation process. Higher speeds and longer durations can lead to more complete separation of the components. However, if the speed is too high or the duration too long, it could potentially damage the components, especially in sensitive biological samples.

In summary, centrifugation is a powerful technique for separating mixtures based on density. By spinning the mixture at high speed, the denser components are forced to the bottom, allowing for their separation from the less dense components.