Page 38 - Lab Manual & Project class 12

LABORATORY MANUAL CHEMISTRY
Theory

Principle for the separation of cations is same as has been explained
in Experiment 5.1. In this case the two cations to be separated are
colourless. therefore, a developer is needed. In the present case,
ammonium sulphide (NH ) S*, can be used to locate the position
4 2
of these ions on chromatographic paper or plate.

Material Required

• Whatman’s filter paper
No. 1 of size 4 cm × 17 cm : One • 1–2% solution
• Gas jar of size 5 cm × 20 cm : One of Pb(NO )
3 2
• Rubber cork fixed with and Cd(NO ) : As per need
3 3
hook in the centre : One • Ehthanol : As per need
• Test tubes : As per need • 6.0 M HNO 3 : As per need

Procedure

(i) Procure a Whatman No. 1 filter paper of size 4 cm × 17 cm.
Ethanol
With the help of a pencil, mark a line at a distance of 3 cm
from one of the ends of this paper.
Lead (ii) Put a spot of the mixture on the marked line with the help of
nitrate Maxbrain Chemistry
a fine capillary.
(iii) Hang the filter paper in a jar containing a mixture of ethanol,
Cadmium 6.0 M HNO and distilled water, in the ratio 8:1:1.
nitrate 3
(iv) Keep the jar as such till the mobile phase (solvent) rises up
to two third of the length of the paper.
(v) Remove the filter paper from the jar, mark the solvent front.
(vi) Spray ammonium sulphide solution on the chromatography
paper to obtain spots of yellow and black colour. Mark the
position of spots with a pencil and allow the paper to dry.
(vii) Measure the distance moved by the solvent front and the
different spots of the cations with respect to the reference
line. This distance is the shortest distance between the
reference line and the centre of different spots.
(viii) Record the observations in tabular form as in Table 5.2.
Calculate the R value for each cation.
f

* Ammonium sulphide is prepared by passing H S gas through the mixture containing 100 mL water and
2
10 mL liquor ammonia for about 45 minutes.
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24-04-2018