To prepare a true solution of common Salt To prepare suspension of fine sant To prepare colloids of starch Steps to distinguish between true solution,suspension and colloids.
Answers
Answer: Aim
To prepare:
Materials Required
Beakers (250 mL), an iron stand, a glass rod, bunsen burner, test tube stand, three funnels, three tripod stands, filter papers, a small torch and China dish.
Chemicals Required
Common salt, sugar crystals, alum powder, chalk powder, fine sand, raw egg, fine soil from garden and distilled water.
Procedure
To prepare a true solution of common salt, sugar and alum in water.
True solution of common salt:
Take a clean and dry beaker, pour 100 mL of distilled water in it and add dry common salt in it.
Stir the content with a glass rod. Common salt dissolves completely to form a true solution.
True solution of sugar:
Take a clean and dry beaker and add 100 mL of distilled water in it, pour few sugar crystals in it arid stir the content with a glass rod. The sugar dissolves in water to form true solution.
True solution of alum:
Take a clean and dry beaker, add 100 mL of distilled water in it and add a pinch of alum powder, stir with a glass rod. The alum dissolves in water to form a true solution.
To prepare a suspension of soil, chalk powder and fine sand in water.
Suspension of sand in water:
Take 100 mL of distilled water in a beaker, add 10 g of fine sand in it. Stir well using a glass rod. Allow it to stand for some time and record your observation.
(It does not dissolve in water)
Suspension of chalk powder in water:
Take 100 mL of distilled water in a beaker, add 10 g of chalk powder in it. Stir well and record your observation,
(chalk + water forms a suspension)
Suspension of soil in water:
Take 100 mL of distilled water in a beaker and 10 g of garden soil to it. Stir the mixture with a glass rod. Allow it to stand for sometime record your observation.
(Soil does not dissolve in water but forms a suspension)
To prepare colloidal solutions of starch and egg albumin in water.
Colloidal solution of starch in water:
Take about 1 g of starch in a china dish, pour 10 mL of distilled water in the dish and stir the mixture. Now take 90 mL of hot, boiling water.
(Heat the water in beaker using Bunsen burner)
Stir the contents of the china dish continuously and pour the contents in the boiling water. Allow the contents to cool. Record your observation.
(The starch + water solution is colloidal in nature.)
Colloidal solution of egg albumin in water:
Take 10 ml of water in a beaker. Break an egg and discard the egg shells. Separate the white portion of egg from the yellow part. Add a very small quantity of egg albumin to it. Stir the contents thoroughly with the help of a glass rod. Then add 90 mL of distilled water with continuous stirring and few drops of dil. acid (dil. HCL, dil.H2S04). Record your observation.
(Egg albumin + water solution is colloidal in nature.)
To distinguish the above formed solutions on the basis of transparency, filtration criterion and stability:
Take one true solution —> salt + water
Take one suspension —> chalk + water
Take one colloidal solution —>egg albumin + water
Transparency:
Take 3 test tubes with a colloid, suspension and true solution in each respectively. Paste a white paper with tick mark on one side of each test tube. Look at the tick mark through the contents of the three test tubes from the other side. Check for the transparency of tick mark.
Record your observations.
Filtration Criterion:
Take 3 tripod stands, place a funnel over each stand. Fix the filter paper in the funnel and check for the filtration criterion.Record your observations.ncert-class-9-science-lab-manual-solution-colloids-suspension-8
Stability Criterion:
Take 3 test tubes with a colloid, suspension and true solution in each respectively. Shake all the test tubes and keep them in the test tube stand, allow it to stand for 5 minutes.
Record your observations.
Observation Table
ncert-class-9-science-lab-manual-solution-colloids-suspension-9
Precautions
Use test tube holder for heating/boiling of water.
Do not waste the chemicals and distilled water. Use it wisely.
Always stir the contents in the test tube nicely and gently.
Use only distilled water to make solutions.
Answer:
Introduction
Solution: It is a homogeneous mixture of two or more substances. Solutions can be solid solutions e.g. alloys; liquid solutions e.g. lemonade and gaseous solutions e.g. air.
A solution is made up of solute and solvent.
Solute: The component of the solution that is dissolved in the solvent is called the solute.
Solvent: The component of the solution that dissolves the other component in it is called solvent.It is the amount of solute present in a given amount of solution. Amount of solute
concentration\quad of\quad a\quad solution\quad =\quad \frac { Amount\quad of\quad solute }{ Amount\quad of\quad solution }
A solution is always transparent, light passes through it without scattering as the solute particles are very small in size. The solution is homogeneous and does not settle. A solution cannot be filtered but can be separated using the process of distillation. For example, a solution of sugar in water.
Types of True Solution: Depending on the nature of solute and solvent, we can get variety of solutions.
A suspension is cloudy and heterogeneous mixture. The particles are larger than the particles of solution and can be filtered. A suspension settles when it is allowed to stand for some time. The particles can be seen with the naked eyes.
The particles of a suspension scatter a beam of light passing through it and make its path visible.
A colloid particle size is intermediate between a solution and a suspension. It does not separate out on standing and cannot be filtered. Colloids show the Tyndall effect. Light passing through a colloid shows dispersion. It is homogeneous to naked eyes, e.g. milk.
Types of Colloidsncert-class-9-science-lab-manual-solution-colloids-suspension-1