Page 64 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

What is the reason?
Which liquid is seen at the bottom? Why?

Can you suggest a method to separate kerosene and water from
this mixture?
Separating funnel is an apparatus used for separating immiscible
liquids from their mixture.

Look at the picture showing the separation of liquid mixture
with the help of a separating funnel. (Fig. 4.9)
Sublimation

Hope you remember collecting iodine vapour by heating iodine
crystals. Iodine is a substance that changes directly into gas on
heating without changing into liquid.

Which other substances show the same property?
Fig. 4.9
Take naphthalene, camphor and ammonium chloride in separate Separating Funnel
test tubes. Heat them and observe. Do they melt into
liquid? The process in which a solid, when heated, Cotton
changes directly into gas without melting into liquid is
Ammonium
called sublimation. This method can be used to separate chloride Funnel
vapours
the components which have the property of sublimation Solidified
ammonium
from the mixture. chloride
Look at the given picture (Figure 4.10) showing the
arrangement for separating the components of a mixture
China dish
of ammonium chloride and sand. Observe the picture
and write down the procedure. How did you obtain pure
ammonium chloride? Burner

Centrifugation

This is a method for separating components from a Fig. 4.10 Sublimation of ammonium
mixture, based on the difference in the mass of particles. This chloride
method is used in clinical laboratories to separate blood cells
from blood samples and also for the quick separation of the
precipitate obtained during chemical experiments. The liquid
containing the sample is taken in a test tube and is rotated about
a central point in the instrument. The particles with higher mass
then get separated, away from the centre and those with lower
mass remain closer to the centre.

Basic Science VIII 63 63
Basic Science VIII