Solution, Colloids, Suspension

EXPERIMENT
AIM
To prepare
1. A true solution of common salt, sugar and alum.
2. A suspension of soil, chalk powder and fine sand in water.
3. A colloidal solution of starch in water and egg albumin in water and distinguish
between these on the basis of
o transparency
o filtration
o stability.
MATERIALS REQUIRED
Test tubes, beakers, water, common salt, sugar, alum, soil, chalk powder, fine sand, egg
albumin, starch, funnel, glass rod, filter paper.
THEORY
1. A true solution has particle size < 10-9 m. It is a homogeneous mixture which is clear
and transparent. It passes through the filter paper easily and is stable.
2. Colloid has particle size 10-9 m- 10-6 m. It is heterogeneous and is translucerft. It
passes through filter paper and is stable.
3. The particle size of Suspension is >10-6 m. It is heterogeneous and opaque. Its
particles do not pass through filter paper and settle under gravity when left
undisturbed for sometime.
PROCEDURE
Preparation of solutions/mixtures
1. Take 8 beakers and label them as A, B, C, D, E, F, G and H and add 50 ml of water to
each of these beakers.
2. Add samples of salt, sugar and alum to beakers A, B and C. Stir to make clear
solution.
3. Add soil, chalk powder and fine sand to beaker D, E and F. Stir for sometime.
4. Add a small amount of starch to the water and boil the content in beaker G.
In beaker H, add egg albumin and stir vigorously.
5. Observe the mixture and record them in the table given below.
OBSERVATION TABLE
RESULTS
1. Beaker A – Common salt forms a true solution in water.
2. Beaker B – Sugar forms a……………. in water.
3. Beaker C – Alum forms a …………….in water.
4. Beaker D – Soil forms a……………. in water.
5. Beaker E – Chalk Powder forms a……………. in water.
6. Beaker F – Fine sand forms a……………. in water.
7. Beaker G – Starch forms a……………. in water.
8. Beaker H – Egg albumin forms a …………….in water.
PRECAUTIONS
1. Distilled water should be used.
2. The components should be mixed in small amounts.
3. Fold the filter paper properly and moisten it before use.
4. Glass rod should be clean.
5. Wash your hands properly with soap after experiment.

Mixture and Compound

EXPERIMENT
AIM
To prepare
(a) a mixture
(b) a compound using iron filings and sulphur powder and distinguish between these on the
basis of:
 1. appearance, i.e. homogeneity and heterogeneity
2. behaviour towards a management
3. behaviour towards carbon disulphide (a solvent)
4. effect of heat
MATERIALS REQUIRED
China dish, tripod stand, wire gauze, iron filings, sulphur burner, test tube stand and test
tube holder.
THEORY
Formation of mixture is a physical change while formation of compound is a chemical
change. Mixture may be homogeneous or heterogeneous while compounds are always
homogeneous. In a mixture, components retain their individual properties while the
components of a compound lose their individual properties. The components of a mixture
can be separated by physical methods while the components of compounds cannot be
separated by physical methods.
PROCEDURE
Preparation of mixture of iron and sulphur:
Take 7 g iron filing and 4 g sulphur powder in a petri dish and mix them properly. Label this
mixture as A.
Preparation of compound iron sulphide:
Take 7 g iron filing and 4 g sulphur in a china dish. Heat this mixture gently and then
strongly. Stir constantly till black mass or compound of iron and sulphur is formed.
Cool the content of china dish and powder the black mass. Label compound powder as B.
PROCEDURE, OBSERVATION AND INFERENCE

RESULT
1.
1. ‘A’ is a mixture which is prepared by mixing iron filings and sulphur.
2. ‘B’ is a compound which is formed by strongly heating a mixture of iron filings and
sulphur. The chemical equation for this change is as follows:

1. Mixture of iron filings and sulphur is heterogeneous while the compound iron sulphide
is homogeneous.
2. Properties of FeS are different from the properties of its constituents.
PRECAUTIONS
1. Handle the chemicals carefully.
 2. Do not bring CS2 near the flame as it is highly inflammable.
3. Heating of mixture of iron filing and sulphur should be done in china dish.
4. Wash your hands properly with soap after the experiment.

Types of Reactions and Changes

EXPERIMENT
AIM
To carry out the following reactions and classify them as physical or chemical changes.
1. Iron with copper sulphate solution in water
2. Burning of magnesium in air
3. Zinc with dilute sulphuric acid
4. Heating of copper sulphate
5. Sodium sulphate with barium chloride in the form of their solutions in water.

(1) Reaction between Iron and Copper Sulphate solution in water

MATERIALS REQUIRED
Two iron nails, CuS04 solution, test tube, clamp stand, thread.

THEORY
Pure iron is greyish in colour. Pure copper is reddish brown in colour. Due to the presence of
Cu2+ ions, aqueous C solution of copper sulphate is blue. Due to the presence of Fe 2+ ions,
aqueous solution of ferrous sulphate is pale green. Iron being more reactive than copper
displaces copper from its salt solution.

PROCEDURE
1. Clean an iron nail by rubbing with sand paper so that it appears greyish.
2. Take two test tubes and labelled them as A and B. In both test tubes, add 10 ml of
freshly prepared copper sulphate solution and fix these test tubes in two separate
clamp stands (Fig 4.1).
 3. Tie a thread to the nail and hang it in test tube B. Care should be taken so that the
iron nail is completely immersed in CuS04 solution. Tie other end of thread to stand as
shown in Fig 4.1.
4. Keep the other iron nail on a white sheet of paper.
5. Leave the set-up undisturbed for sometime.
6. Remove the nail from the solution and keep it along the side of second iron nail on
sheet of paper. Record your observations.
OBSERVATION AND INFERENCE

RESULT
The reaction between Fe and CuS04 shows that Fe is more reactive than Cu and the reaction
is a displacement reaction.
PRECAUTIONS
1. Clean the iron nail properly by rubbing with sand paper.
2. Copper sulphate solution is poisonous, so, handle it with care.
3. During experiment, the test tubes should not be touched or disturbed.
4. After completing experiment, iron nail coated with copper should not be touched.
(2) Burning of Magnesium in air
MATERIALS REQUIRED
Magnesium Ribbon, burner, tongs, watch glass, pH paper strip/red litmus paper.
THEORY
Magnesium is a very active metal. It reacts with oxygen to form magnesium oxide.

During this process two elements viz, magnesium and oxygen combine together to form a
single compound magnesium oxide. Such type of reactions are called combination reactions.
Magnesium oxide is basic in nature because when this is dissolved in water it forms
magnesium hydroxide which is basic in nature.

Magnesium oxide turns red litmus solution blue.

PROCEDURE, OBSERVATION AND INTERFENCE

RESULT
Mg burns in air giving out a flash of bright white light and combines with oxygen to form
basic magnesium oxide. MgO is basic in nature
PRECAUTIONS
1. Magnesium ribbon should be cleaned by rubbing with sand paper.
2. Hold magnesium ribbon using tongs while burning it.
3. Do not look at the bright light associated with burning Mg directly. Use sun glasses.
4. White powder or magnesium oxide should not be touched.
(3) Reaction of Zn with dil. Sulphuric Acid
MATERIALS REQUIRED
Zinc granules, dil. H2S04 , clamp stand, boiling tube, cork fixed with a fine capillary tube.
THEORY
Zinc being more reactive or lying above hydrogen in the reactivity series, displaces
hydrogen from dil. acids.
Zn(s) + H2S04 (aq) → ZnS04 (aq) +H2(g)
PROCEDURE,OBSERVATION AND INFERENCE

RESULT
Zinc reacts with sulphuric acid to produce hydrogen gas and zinc sulphate.
Zn(s) + H2S04 (aq) → ZnS04 (aq) +H2(g)
PRECAUTIONS
1. Handle the chemicals with care.
2. Use a small jet to test hydrogen gas, as hydrogen gas burns instantaneously with an
explosion.

(4) Heating of Copper Sulphate

MATERIALS REQUIRED
Hydrated copper sulphate, test tube, test tube holder, burner, pH paper or blue litmus
paper.
THEORY
Chemical formula of copper sulphate pentahydrate is CuS0 4.5H20 . It contains five moles of
water per mole of copper sulphate. Because of water of hydration, the colour of copper
sulphate pentahydrate is blue. When it is heated, it loses water molecules and turns to white
coloured anhydrous copper sulphate.

The above process can be reversed. When water is added to anhydrous copper sulphate, its
colour changes to blue. This shows that coloured hydrated copper sulphate has regained.

On further heating, anydrous copper sulphate decomposes to form sulphur trioxide gas and
copper oxide.

The whole change of heating of copper sulphate pentahydrate can be given by the following
equation:

The reaction in which a substance breaks down to form more than one products is called
decomposition reaction.
PROCEDURE,OBSERVATION AND INFERENCE

RESULT
The hydrated copper sulphate loses water of crystallisation on gentle heating and becomes
dirty white. On further heating strongly, it decomposes to black copper oxide and pungent
smelling sulphur trioxide.
PRECAUTIONS
1. Copper sulphate is a poisonous substance. Do not touch or taste it.
2. Sulphur trioxide coming in contact with atmospheric moisture forms sulphuric acid.
So, contact with sulphur trioxide must be avoided.
3. In the beginning of experiment, copper sulphate should be heated gently. But after
the formation of anhydrous copper sulphate test tube should be heated strongly.

(5) Reaction between Sodium Sulphate and Barium Chloride in the form of their
Aqueous Solutions
MATERIALS REQUIRED
Test tube, test tube holders, aqueous solution of sodium sulphate and barium chloride.
THEORY
On mixing the solutions of sodium sulphate and barium chloride, a white precipitate of
barium sulphate is formed which in insoluble in water. This chemical change can be
represented by the following chemical equation:

In this reaction, white precipitate of BaS04 is formed by the reaction ofS0 42-and Ba2+. The
other product formed is sodium chloride which remains in the solution. Such reactions in
which there is an exchange of ions between the reactants are called double displacement
reactions.

PROCEDURE, OBSERVATION AND INFERENCE

RESULT
The reaction between Na2S04 (aq) and BaCl2 (aq) yields an insoluble white precipitate of
BaS04, indicating that the reaction is a double displacement reaction.
PRECAUTIONS
1. Use the chemicals in small amounts.
2. Wash your hands with soap after completing the experiment.

CBSE Class 9 Science Practical Skills – Slide of

Onion Peel and Cheek Cells
EXPERIMENT (a)
AIM
To prepare stained temporary mount of onion peel cells and to record observations and
draw labelled diagrams.
MATERIALS REQUIRED
Onion, plain slides, coverslip, watch glass, needles, forceps, brush, blade, safranin, blotting
paper, glycerine and compound microscope.
THEORY
Onion is a multicellular plant. Like other plant cells, the cell of onion peel consists of a cell
wall, cell membrane, cytoplasm, a large vacuole and a nucleus. The nucleus lies at the
periphery of cytoplasm and vacuole is located in the centre. Presence of large vacuoles and
cell wall confirms that cells of onion peel are plant cells.
PROCEDURE
 1. Take a piece of onion and bend it to remove the transparent membranous structure
called onion epidermal peel. With help of forcep remove the peel from its inner
side.
2. Place the peel in water in a watch glass.
3. Add a few drops of stain safranin, to the watch glass containing the peel for staining.
4. Now, wash the leaf peel with water and transfer it on to a clean slide with the help of
brush.
5. Remove extra water from the slide surrounding the peel with the help of blotting
paper.
6. To this slide, add a drop of glycerine over the peel and place the coverslip in a
manner to avoid entry of air bubbles.
7. Soak away the extra glycerine with blotting paper.
8. Examine slide under the microscope.

OBSERVATIONS
1. A large number of rectangular cells with distinct cell wall can be observed.
2. Cytoplasm is seen as thin layer of deep coloured substance on inner surface of cell
wall.
3. A big central vacuole is present in the cell.
 4. A deeply stained round body called nucleus is seen in each cell.

RESULT
1. The epidermal peel of onion comprises of rectangular shaped cells. Each cell
comprises of a nucleus, a central vacuole, thin layer of cytoplasm and cell wall.
2. As cell walls and large prominent vacuole are present in each cell, the cells placed
under observation are plant cells.
PRECAUTIONS
1. Always take a clean slide and hold it by its edges to avoid making the slide dirty.
2. Peel should be properly stain. Avoid under-staining or excessive staining of the peel.
3. Always transfer the peel with the help of brush.
4. Mounting of the peel should be done in centre of slide.
5. Avoid folding of the leaf peel.
6. Remove extra glycerine with the help of blotting paper.
7. Avoid entry of air bubbles while placing the cover slip.
Plant and Animal Tissues
EXPERIMENT (a)
AIM
To identify parenchyma and sclerenchyma tissues in plants, from prepared slides and to
draw their labelled diagrams.
MATERIALS REQUIRED
Prepared slides of parenchyma, collenchyma and sclerenchyma, compound microscope.
You can also Download tissues class 9 notes PDF to help you to revise complete Syllabus
and score more marks in your examinations.
THEORY
A group of cells that are similar in structure and work together to achieve a particular
function forms a tissue. The main types of plant tissues include-

PROCEDURE
1. Observe the prepared slides of all the plant tissues one by one.
2. First focus the slide at low power and then observe it at high power.
3. Study the characters and draw the diagrams in your notebook.
OBSERVATIONS
IDENTIFYING FEATURES
I. Parenchyma
1. Cells of Parenchyma tissue are isodiametric.
2. Intercellular spaces are present in between the cells.
3. Parenchymatous cells possess large central vacuole and peripheral cytoplasm with a
nucleus.
4. These are generally present in the soft parts of plants like leaves, roots, flowers, etc.
 5. The important functions of parenchymatous cells are storage, photosynthesis, etc.

II. CoIIenchyma
1. Collenchymatous cells are somewhat oval to elongated.
2. Each cell possesses large central vacuole and peripheral cytoplasm with prominent
nucleus.
3. Thickenings are present at corners of cells. Thickening comprise of cellulose and
pectin.
4. Intercellular spaces are absent.
5. Collenchymatous cells are commonly present below the epidermis in petiole, leaves
and stems. Its
6. main function is to provide mechanical strength.

III. Sclerenchyma
1. Cells of sclerenchyma tissue are dead with highly thickened walls.
2. Thickenings consist of lignin.
3. There are two types of sclerenchyma cells:
o fibres which are elongated cells with tapering ends and
 o sclereids (also called stone cells), which are roughly isodiametric cells with narrow
cavities.
4. Sclerenchymatous cells have pits which act as connections with adjacent cells.
5. The main function of sclerenchyma is to provide support and mechanical strength to
the plant.

PRECAUTIONS
1. Handle the microscope carefully.
2. Always focus the slide first at low power (10 x) and then at high power (40x).
EXPERIMENT (b)
AIM
To identify striped muscle fibres and nerve cells in animals, from prepared slides and to
draw their labelled diagrams.
MATERIALS REQUIRED
Prepared slides of non-striated, striated and cardiac muscle fibres and nerve cells,
compound microscope.
THEORY
A tissue is a group of cells that are similar in structure, origin and function.

PROCEDURE
1. Clean the microscope and adjust the light in microscope.
2. Place the prepared slide of tissue on the stage of microscope and focus first at low
power and then at high power.
3. Observe the structure of tissues and draw the diagram of tissues as seen under
microscope.
OBSERVATIONS
I. Striated Muscles or Striped or Skeletal Muscles
1. Striated muscle cells are cylindrical, elongated and enclosed in a membrane called
sarcolemma.
 2. These muscle cells are multinucleated.
3. Striated muscles show presence of light and dark bands which gives it striped
appearance.
4. These muscles are present attached to the skeleton of the body.
5. They are voluntary muscles (i.e., work according to our will).

II. Non-striated Muscles or Unstriped or Smooth Muscles

1. The cells are spindle-shaped.
2. Nucleus is centrally located.
3. These muscles do not show striations {i.e., no light and dark bands).
4. Non-striated muscles are involuntary in nature.
5. They are commonly found in alimentary canals and blood vessels.

III.Cardiac Muscles
1. Cardiac muscle cells are long, branched and uninucleate.
2. These show the presence of intercalated discs.
3. They show alternate light and dark bands.
 4. These are involuntary muscles and responsible for rhythmic contraction and
relaxation of heart.
5. Cardiac muscles are present only in walls of heart.

NERVE CELL
1. Nerve cell comprises of a cell body or cyton with a single nucleus and cytoplasm.
2. Many small cytoplasmic projections arise from cyton which are called dendrons. The
dendrons divide further to form dendrites.
3. A long cytoplasmic projection arising from cell body is called axon.
4. A myelin sheath is present over the axon in some nerve fibres, these are called
myelinated nerve fibre and when myelin sheath is absent these are called non-
myelinated nerve fibres.
5. Myelin sheath is not continuous. There are gaps along the entire length. Each gap is
called nodes of Ranvier.
6. Nerve cells help in conduction of nerve impulse.

PRECAUTIONS
1. Handle the microscope carefully.
2. Always focus the slide first at low power and then at high power.