Investigatory Project

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This project has been developed in the chemical laboratory of BRIGHT DAY SCHOOL,VADODARA. For successful completion of the project named,STUDY OF DIFFUSION OFSOLIDS IN LIQUIDS. I would like to thanks our working chemistry teacher Mrs. NIDHI for her guidance and help I would like to thanks VISHAL SIR for providing me the lab apparatus.

At the end I would like to thanks all those who were associated with me, whose cooperation made the development of the project a worthy experience.


Diffusion is the chemical process when molecules from a material move from an area of high concentration (where there are lots of molecules) to an area of low concentration (where there are fewer molecules). This happens through otherwise random movement. Diffusion usually happens in a gas although it can happen in a liquid. It is possible to see diffusion happening when two liquids are mixed in a transparent container. It describes the constant movement of particles in all liquids and gases. These particles move in all directions bumping into each other. Diffusion may be also referred as the process by which molecules intermingle as a result of their kinetic energy of random motion. The diffusion process continues until a homogenous solution is obtained.The diffusion of solute into solvent is, in fact, a bilateral process. The characteristics are as follows: Solute molecules moving up into the solvent. The solvent molecules moving down into the solution.This inter-mixing of solute and solvent molecules is a continuous process and ultimately a solution of uniform concentration is formed.Thus Diffusion can be defined as"The tendency to equalize concentration in all parts of the solution which is responsible for the diffusion of the solute."Hence, the diffusion of any solute can also take place when two solutions of unequal concentrations are kept in same vessel or in contact.

The diffusion takes place very rapidly in case of gases and to a lesser extent in case of liquids, whereas solids do not show this process of diffusion with each other. But what we can observe in case of solids is that the diffusion of solids in liquids takes place at a very slow rate. If a solid is kept in contact with an excess of solvent in which it is soluble, some portion of the solid gets dissolved. We know that this process is known as dissolution of a solid in liquid and this process has taken place due to the diffusion of solid particles into liquid. Molecules of solute are in constant random motion due to the collision between molecules of solute and that of the solvent.

Also as the temperature is raised, kinetic energy of molecules increases which thereby increases the number of collisions. Particles of different substances move at different ratese.g.,when different colored inks are placed in water at constant temperature, they diffuse at different rates. The speed of the movement of solid particles depends upon (a) Temperature(b) Size of the particles (c) Mass of the particle.

Also the particles of larger mass will have slow rate diffusion because force of gravity slows down the upward rate of diffusion.


Rate of diffusion depends upon:-

Temperature: As temperature increases, the kinetic energy of the particles increases so the speed of particles also increases which thus increases the rate of diffusion.

Size of the particle: As the size of particle increases, rate of diffusion decreases.

Mass of the particle: As the mass of the particle increases the rate of diffusion decreases.


AIM: To study diffusion when copper sulphate is brought in contact with water (liquid).REQUIREMENTS: Copper sulphate crystals, 100ml beaker. PROCEDURE: Take about 2g of copper sulphate crystals in 100ml beaker. Add about 50ml of water and allow it to stand for few minutes. Note the development of blue colour in water. Allow to stand further till it is observed that all copper sulphate disappears. Note the violet colour change in water. Repeat the above steps in another beaker with the same amount of COPPER SULPHATE but stir the solution for sometime till a homogenous mixture is obtained. Note the time taken for the solid to get diffuse in both the different cases under a constant temperature.





DISCUSSION: Stirring facilitates the diffusion of the copper sulphate in water. This is probably due to increase in the kinetic energy i.e., randomness of the molecules of solid particles by both stirring and increase in temperature of the system.

CONCLUSION: When solids such as copper sulphate, potassium permanganate are brought in contact with liquids such as water, intermixing of substances, i.e. diffusion takes place. Also the rate of diffusion of a solid in a liquid increases on stirring

EXPERIMENT NO 2AIM: To study the rate of diffusion of solids in a liquid is dependent on the molecular mass of the solids.REQUIREMENTS:Two 250 mL beakers, measuring cylinder, stop watchCHEMICALS:Potassium dichromate, copper sulphate and distilled water.PROCEDURE:1. Powder potassium dichromate and copper sulphate well in a clean pestle and mortar, weigh 2 g of each.2. Take 100 mL of distilled water in a clean beaker with the help of a measuring cylinder.3. Add 2 g of potassium dichromate into it and immediately start a stop watch. Note the time for complete dissolution of the dichromate.4. Similarly, find out three times for complete dissolution of 2 g of the powdered copper sulphate in 100 mL of water.OBSERVATION:Room temperature = 27CWeight of the solid taken = 2 gVolume of distilled water taken each time = 100 mLMolecular mass of CuSO4 = 249.5 g/molMolecular mass of K2Cr2O7 = 294 g/mol

Molecular mass of Cu ion =63.5 g/molMolecular mass of Cr2O7 ion =216 g/molTime for complete dissolution of K2Cr2O7 = _ _ Time for complete dissolution of CuSO4 =_ _ DISCUSSION:It is observed that time taken for complete dissolution of CuSO4 is less as compared to the time taken for complete dissolution of the same amount of potassium dichromate. Thus, it can be said that rate of diffusion of a solid in a liquid depends upon the nature of the solid and their molecular masses, other conditions remaining same. Diffusion rate of potassium dichromate having higher molecular mass than copper sulphate is slower as compared to copper sulphate. That is rate of diffusion of solids in liquids is inversely proportional to the molecular mass of the solid, if other conditions are same.CONCLUSION:Rate of diffusion of a solid in a liquid depends upon molecular mass of the solid.

EXPERIMENT NO 3AIM: To study the effect of temperature on the rate of diffusion of solids in liquids

REQUIREMENTS: Copper sulphate crystals, 200ml beaker, watch glass, wire gauge, burner, tripod stand, thermometer and stop watch. PROCEDURE: Take 5g of copper sulphate each in three beakers. Pour 100ml of distilled water slowly in one of the beakers. Cover this beaker with a watch glass. Pour 100ml of cold water in a second beaker slowly. Place a third beaker containing 100ml of water on a tripod stand for heating. Observe the diffusion process which begins in all the beakers. Record the time taken for the dissolution of copper sulphate in all the three cases.





CONCLUSION: The Rate of diffusion of copper sulphate in water is in the order of Beaker 3 > Beaker 1 > Beaker 2. Thus, the rate of diffusion varies directly with temperature.

H2O (27 C) H2O(12 C) H2O(55 C)


Solid particles and undergo diffusion when they come in contact with liquids. Small particles undergo diffusion more quickly than bigger particles.

When solids such as copper sulphate,potassium permanganate are brought in contact with liquid such as water, intermixing of the substances, i.e. diffusion takes place.

The rate of diffusion varies directly with temperature.


1. NCERT Biology and chemistry Textbook2. WIKIPEDIA3. Diffusionmag.com4. MERIAMWEBSTER.COM5.