Class 9 Record Experiment 4

 EXPERIMENT – 4

Aim
To determine the melting point of ice and boiling point of water.

Theory

1. Melting Point: The temperature at which the solid changes into liquid at the atmospheric pressure is called melting point. For example, ice melts at 0°C to form water.

2. Boiling Point: The temperature at which the liquid boils and changes into gaseous state at the atmospheric pressure is called boiling point. For example, water boils at 100°C to form water vapour (at 76 cm pressure).

3. Latent Heat of Fusion: The heat energy absorbed during the melting of ice is stored in the water formed, this energy is called latent heat of fusion. The amount of heat energy that is required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point is known as the latent heat of fusion.

4. Latent Heat of Vaporisation: The heat energy absorbed by water when it changed its phase to steam, this hidden heat is called latent heat of vaporisation.

Conditions Affecting Melting Point and Boiling Point

Materials Required
Two thermometers, (Celsius scale), boiling tube, a glass rod, two iron stands, a bunsen burner, wire gauze, beakers, tripod stand, distilled water, ice cubes prepared from distilled water.

Procedure
(A)To determine the boiling point of water.

1. Take 25-30 ml of water in a boiling tube and add few pumice stones to it.

2. Clamp the boiling tube on iron stand with two holed cork, in one hole fix the thermometer and in the other one fix the delivery tube.

3. Place the thermometer above the water in the flask as shown in the figure and record its temperature.

4. Place a burner under the boiling tube.

5. Read the temperature and record it in the given observation table till the water boils. Record the reading after the time interval of 1 minute.
   

Observation Table

Result

1. Boiling Point of water  is 100 °C.

2. Once the boiling point is attained the temperature reading on thermometer does not change for sometime.

(B)To determine the melting point of ice.

1. Take a beaker half-filled with the dry crushed ice obtained from distilled water.

2. Suspend a Celsius thermometer from the clamp stand such that the bulb of the thermometer is completely surrounded by ice.

3. Read the thermometer reading and record the temperature after every 1 minute till the ice melts and the thermometer reading remains stationary for 2 minutes.

4. Note the readings in the observation table.
   

Observation Table

Result

1. Melting point of ice is 0 °C.

2. Once the melting of ice begins the temperature remains constant for some time.

Precautions

1. Choose a better  quality thermometer whose graduated scale is clearly readable.

2. Record the temperature in whole numbers.

3. While reading the thermometer the eye level should be parallel with mercury level.

4. Dip only the bulb of thermometer into water/ice.

5. Thermometer should not touch the walls of beaker or boiling tube.

Class 9 Record Experiment 3

 EXPERIMENT – 3 

Aim
To carry out the following chemical reactions and classify them as physical or chemical changes.

1. Iron with copper sulphate solution in water.

2. Burning of magnesium ribbon 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.

Theory

1. Physical Change: When there is no change in the composition of a substance and no change in chemical nature of the substance, such change is called as physical change.

2. In physical change, the interconversion of state takes place. For example,
   

3. 

4. Chemical Change: It is a change which brings change in the chemical properties of matter and a new substance is obtained. For example, burning of oil, fuel.

5. In a chemical change – heat is evolved or taken in, formation of bubbles, gas, fumes takes place, there is a change in colour of the reactants when they form a product.

The chemical reactions are of four types:

1. Combination reaction: Two elements/compounds combine to form a single product.

2Mg (s)+ O2 (g) → 2MgO (s)

CaO (s) + H2O (l) → Ca(OH)2 (aq)

2. Decomposition reaction: When a compound decomposes/breaks due to energy, heat, light or electricity to form simpler substance.

3. Displacement reaction: It takes place when more reactive metal reacts with the salt of less reactive metal and displaces it to form a new compound.

4. Double displacement reaction: In this reaction when two salts are mixed together in solution form then exchange of ions takes place and a new product is obtained.
   E.g.

Materials Required
Test tubes, test tube stand, test tube holder, a pair of tongs, Bunsen burner.

Chemicals Required
Iron filings, copper sulphate solution, magnesium ribbon, zinc granules, dilute sulphuric acid, sodium sulphate and barium chloride solutions and copper sulphate crystals.

Procedure

Iron with copper sulphate solution in water

Burning of magnesium ribbon in air

Zinc with dilute sulphuric acid.


Reaction: Zn(s) + H2SO4 (aq) → ZnSO4 (aq) + H2 (g) 

Heating of copper sulphate salt

Reaction of sodium sulphate and barium sulphate solutions.

Precautions

1. Use all the chemicals in very less quantity.

2. Use test tube holder for heating.

3. Clean magnesium ribbon with sand paper and use fire tongs for holding magnesium ribbon.

4. Handle the acids and alkalies carefully

Class 9 Record Experiment 2

 EXPERIMENT – 2 

Aim
To prepare:

1. a mixture

2. 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 magnet

3. behaviour towards carbon disulphide as a solvent.

4. effect of heat.

Theory

Mixture: When two or more than two substances mix together in any proportion physically and do not show any chemical change, retain their individual properties, then they form a mixture.
Compound: When two or more than two substances combine together chemically in a fixed ratio, such that they can be separated only by chemical means, then a compound is formed.

Differnces between Mixture and Compound:

Mixture

Separation of Iron and Sulphur from its Mixture

Compound

Separation of Iron and Sulphur from its compound

Materials Required
Test tubes, test tube stand, test tube holder, hard glass test tube, Bunsen burner, tripod stand, wire gauze, magnet, China dish and a watch glass.

Chemicals Required
Iron filings, sulphur powder, carbon disulphide.

Procedure

1. Preparation of a mixture of iron and sulphur powder.
   Take a pinch of iron filings and two pinch of sulphur powder, mix them thoroughly. The product obtained is mixture of iron and sulphur. Keep it in a watch glass (A).

2. Preparation of the compound of iron and sulphur.
   Take a pinch of iron filing and a pinch of sulphur powder in a hard glass test tube. Hold it in a test tube holder, heat it on the flame till the contents glow. The reaction between sulphur and iron filings is seen in the test tube and iron sulphide is formed. Transfer the compound formed in a watch glass (B).
   (The mixture of iron filing and sulphur powder can be heated in China dish)
   Record your observations in the table.

Observations

Precautions

1. Heat the mixture of iron and sulphur in hard glass tube or in a china dish.

2. Avoid wasting the chemicals, use very little amount of it.

3. Heating activity should be done carefully.

4. Carbon disulphide is flammable, keep it away from flame