decantation

Question 1

intro

Answer 1

Decantation is a process by which a liquid is separated from a solid. The solid is allowed to settle
and liquid is poured off carefully leaving the settled solid undisturbed.

Question 2

definition

Answer 2

 “Decantation is a process for the separation of mixtures, by removing a layer of liquid, generally one
from which a precipitate has settled”.
 Decanting is a process to separate mixtures. Decanting is just allowing a mixture of solid and liquid or
two immiscible liquids to settle and separate by gravity.
 This process can be slow and tedious without the aid of a centrifuge. Once the mixture components
have separated, the lighter liquid is poured off leaving the heavier liquid or solid behind.
 Decantation is a process to separate mixtures by removing a liquid layer that is free of a precipitate, or
the solids deposited from a solution. The purpose may be to obtain a decant (liquid free from
particulates) or to recover the precipitate.

Question 3

process

Answer 3

 In laboratory conditions, small volumes of mixtures are decanted in test tubes. If time is not a concern,
the test tube is kept at a 45° angle in a test tube rack.
 This allows the heavier particles to slide down the side of the test tube while allowing the lighter liquid
a path to rise to the top. If the test tube were held vertically, the heavier mixture component could
block the test tube and not allow the lighter liquid to pass as it rises.

Question 4

purpose/aim

Answer 4

 The purpose of decantation is to separate insoluble liquids from solids.
 The purpose may be either to produce a clean decant, or to remove undesired liquid from the precipitate
(or other layers).
 DECANTER: A decanter is a vessel used to hold the decantation of a liquid which may contains
sediments.

Question 5

principles

Answer 5

The principles of decantation are:
 Sedimentation
 Centrifugation
Decantation is a “pouring off” of a liquid from a solid/liquid mixture. The mixture is allowed to settle,
and the liquid is removed while preventing the solid from escaping.

Question 6

when is it used

Answer 6

Decantation is used when one is separating part of a mixture from another and when the particles or
sediments are too fine to be filtered from a liquid.

Question 7

procedure

Answer 7

The steps of decantation are given below:
1. Mixture in the container is allowed to stand for sometime
2. The solid particles will settle in time
3. The upper layer of the liquid gets cleaner
4. Separate the course particles of a solid from a liquid by pouring the liquid to a new container by the
process of decantation

Question 8

examples

Answer 8

1. Oil & Water: Oil floats on the top of the water. Decanting the mixture allows the oil to be poured off
   the water.
2. Dirt and water: Muddy water can be cleared up by decanting. The soil will sink to the bottom of the
   tube allowing the clear water to be poured off.
3. Cream & Milk: Cream is separated from milk by decantation. Cream rises to the top of the milk
   mixture and easily skimmed off.
4. Blood & plasma: A centrifuge is necessary for this decantation. Plasma can be removed from the
   blood by decantation.

Question 9

disadvantages

Answer 9

 It cannot be used to separate a mixture of a liquid and a light solid, such as chalk in water. The particles
of chalk are suspended I the water. They are so light that they do not sink down to the bottom for a
long time.

Question 10

applications

Answer 10

1. It is employed in washing precipitates by adding the wash solution, allowing the solid to settle, and
   pouring off, continuing the process until free from impurities. If the solid to be separated settles rather
   rapidly, decantation may be employed to the advantage.
2. In order to separate an insoluble solid from a liquid.