A technique used in separating a less-dense substance from a denser one is called
A. Decantation
B. Distillation
C. Filtration D. Evaporation
The correct answer and explanation is:
Correct Answer: A. Decantation
Decantation is a physical separation technique used to separate mixtures of liquids and solids or two immiscible liquids based on differences in density. This method is especially useful when the components of a mixture do not dissolve in each other and one substance is clearly denser than the other. The process involves gently pouring the less-dense substance off the top, leaving the denser substance behind in the container.
In practice, decantation is commonly applied when separating oil from water, where oil, being less dense, floats on top of the water. Another common example is separating muddy water. After allowing the mud to settle at the bottom due to gravity, the clearer water at the top is gently poured off. This process avoids disturbing the sediment and effectively separates the two components.
Decantation does not require specialized equipment. It can be performed with simple containers and by relying on gravity to assist in the settling process. The key principle behind decantation is the density difference between substances. The substance with the lower density will remain at the top and can be poured or siphoned off without mixing with the heavier component.
In contrast, distillation is used to separate mixtures based on boiling points, filtration separates solids from liquids using a filter medium, and evaporation involves removing a liquid to recover the dissolved substance. These methods are effective but serve different purposes.
Therefore, for separating a less-dense substance from a denser one, decantation is the most suitable method. It is simple, efficient, and commonly used in laboratory and household settings to achieve basic physical separations based on density differences.