-
Weigh accurately 100 grams of
the dyestuff and note the exact balance reading as A grams.
-
transfer this dyestuff in to a
500 ml clean beaker
-
slowly add hot distilled water
(60C) and make it in to a paste and dilute it further with cold distilled water.
-
transfer the dissolved portion
of the dyestuff liquor in to the 500 ml standard measuring flask (SMF).
-
to the un-dissolved semi-solid
mass of dyestuff remaining in the beaker add further quantity of distilled
water and dissolve it. Again transfer the dissolved dye in to the standard
measuring flask. Repeat the process until about 400ml of water is added
into the SMF. Now make the remaining quantity of dyestuff in the beaker in
to a slurry by adding further water and transfer the whole slurry in to the
SMF flask
-
Make up the volume of water to
500ml in the SMF.
-
Shake well for about 10 minutes.
-
Weigh a whatman filter paper
blank - let the weight be B grams.
-
Filter the dissolved dye-liquor
through a pre-weighed whatman filter paper-1 - do not add any water
during filtration. make use of the solute only for all transfers.
-
After filtering dry the filter
paper at 110C for 3 hours. cool it in a decicator and weigh the paper along
with the content. Let the Weight be C grams.
-
Then the un-dissolved dyestuff
in the filter paper (D) = C - B grams
-
The the solubility of the
dyestuff (S1) = (A -D)/500 x 1000 grams per liter.
-
To counter check this value,
measure 100 ml of the clear dissolved dyestuff solution and transfer in to a
250 ml pre-weighed drying crucible. Evaporate and dry it at constant
temperature of 95C for 3 hours.
-
Check for drying in to powder
mass and cool the crucible; weigh it. Find the weight of dissolved
dyestuff - x grams.
-
So 100 grams of the solution
contain x grams of dyestuff - calculate for 1000 ml. let it S2.
-
Compare S1 and S2 - if the
difference is very small then average out the two readings or repeat until
you get both readings are very close.
