Distinguishing Between Solutions

Materials Required:

Real Lab Procedure:

Preparation of a true solution of common salt, sugar and alum

Take three beakers with 90 ml water in each. Label them as A, B, and C. Add 10 g of finely powdered common salt, sugar and alum (phitkari) in beakers A, B and C respectively. Stir the solutions in each beaker thoroughly with the help of a glass rod and when ready keep them for further use.
 

  • Preparation of a suspension of soil, chalk powder and fine sand in water

Take three beakers. Put 90 ml of water in each beaker. Label them as D, E, and F. Add 10 g of  fine soil (without litter), fine chalk powder and fine sand in beaker A, B and C respectively. Stir the contents of each beaker well with the help of a glass rod.

  • A colloidal of starch in water

Mix 1% dry corn starch with 3 ml of distilled water. To this add 97 ml of boiling distilled water. Stir it well. Heat it for 2 minutes stirring the solution constantly. Cool it and store it for further use. Label the test tube as G.

  • A colloidal of egg albumin in water

Take 1 g of egg albumin (the colourless fluid found around the yellow yolk) and 5 ml of distilled water in a beaker. Mix it well. Slowly add 95 ml of distilled water while stirring continuously. After mixing, add a few drops of acid (dil.HCl/dil.H2SO4 or acetic acid) and stir well. The clear solution of albumin and water will become turbid. Label the test tube as H.

Property to be tested Experimental procedure Observations Inference
1.Transparency Paste small strips of same coloured cellophane paper on one side of each test tube, i.e., A, B, C and D, E, F and G and H.
Arrange test tubes in groups according to solution, suspension and colloid. Now observe the coloured paper of each test tube of the set from the other side of the test tube through the liquid one by one.
Coloured spot is clearly seen from the other side of test tubes A, B and C. A true solution is transparent.
Coloured spot is not visible from other side of test tubes D, E and F. A suspension is opaque.
Coloured spot appears dim from the other side of test tubes G and H. A colloid is translucent.
 2. Filtration
Filter the contents of test tubes A, B and C separately. No residue is left on the filter paper. A clear filtrate is obtained. Solid particles cannot be separated from true solution by filtration.
Filter the contents of test tubes D, E and F separately.
 
Particulate suspension is seen on the filter paper in each case but filtrate is a clear liquid. Suspended components of a suspension can be separated by filtration.
Filter the contents of test tubes G and H separately. No residue left on the filter paper in both the cases. But filtrate obtained is translucent. Components causing colloid  cannot be separated by filtration.
 3. Stability Leave the test tubes A, B, C, D, E, F, G and H for some time  (15 to 20 minutes). No change. The solution remains as it is without any settlement in test tubes A, B and C. The true solutions are stable and do not show deposition of components.
In test tubes D, E, F there is gradual settlement of solid particles at the bottom. Suspension is unstable and show settlement of heavier particles.
No change is observed in test tubes G and H. Colloids are stable. Their solute particles do not settle down when left undisturbed.

Simulator Procedure:

You can select the property from ‘Select the property’ drop down list.

You can select the sample by clicking on the respective icon.

Place the mouse over each test tube to see the names of the samples selected.

Transparency

  • To check the transparency of the sample, drag the cellophane paper behind the sample.
  • You can see the inference by clicking on the inference icon.
  • Click on the ‘Reset’ button to redo the experiment.

 Filtration

  • To filter the sample, drag the test tube towards the funnel.
  • Click on the funnel to see the zoomed viewed of the filter paper and the residue left behind on the filter paper after filtration.  
  • You can see the inference by clicking on the inference icon.
  • Click on the ‘Reset’ button to redo the experiment.

Stability

  • To check the stability of the sample, click on the ‘Start’ button of the timer and wait for 20 minutes to view the settlement of particles in the sample.
  • You can see the inference by clicking on the inference icon.
  • Click on the ‘Reset’ button to redo the experiment.

Tyndall effect

  • To fix the test tube in the stand, drag the test tube towards it.
  • Drag the light source towards the test tube fixed in the stand, to correctly view the Tyndall effect.
  • You can see the inference by clicking on the inference icon.
  • Click on the ‘Reset’ button to redo the experiment.

Note: Click on the ‘HELP’ button to see the instructions.

Inferences:

  1. Colloidal solutions are somewhat translucent and their particles can pass through filter paper to give translucent filtrate. No residue particles are left as residue on the filter paper.
  2. True solutions are transparent. They pass through filter paper leaving no residue on the filter paper. The filtrate is also transparent.
  3. Suspensions are somewhat  opaque or dull. They leave residue particles on filter paper on filtration. The filtrate is more or less clear and transparent.

Precautions:

  1. While filtering a solution drop the contents along a glass rod into the funnel.
  2. Keep the sample undisturbed while checking stability.
  3. Handle acids carefully. 

 

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