To prepare a suspension of soil, chalk powder and fine sand in water- Class 9th Science Lab Work

To prepare a suspension of soil, chalk powder and fine sand in water and distinguish between these on the basis of:
(i) transparency
(ii) filtration criterion
(iii) stability

In suspension, the particle size is of the order of 10-5 cm or larger which can be seen directly from naked eyes or under ordinary microscope. The suspensions are not very stable and suspended particles settled down after few minutes.

Materials Required
Beakers, Test tubes, Soil, Chalk powder, Fine sand, Glass Rod, Water

Step 1: Three beakers are taken and 100 ml of water is added in each of them and labelled them as A, B and C respectively.
Step 2: 10g of fine soil (without litter), fine chalk powder and fine sand is added in each beaker separately.
Step 3: Solution is stirred with the help of glass rod.
Step: Put the solutions in test tubes and labelled them as A, B and C.
Observation Table
Property Experimental Procedure Observation Inference
Transparency Small strip of cellophane paper is pasted on each test tubes and the coloured paper of each test tube is observed from other side of test tube. Coloured spot is not visible from other side of test tubes. A suspension is opaque.
Filtrate Contents of test tubes labelled as A, B and C are filtrated. Particulate suspension is seen on the filter paper but filtrate is a clear liquid. Suspended components of a suspension can be separated by filtration.
Stability Leave the test tubes without disturbance for 20-25 minutes. Settlement of solid particles can be observed at the bottom. The suspensions are not stable and show deposition of heavier components.

Results and Discussion
Suspension are opaque. They left residue on filter paper on filtration. The filtrate is somewhat clear or transparent.

(i) Handle the materials and solutions with care.
(ii) While filtering a solution drop the contents along a glass rod into the beaker.
(iii) Keep the sample undisturbed while checking stability.

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