To study the diffusion of

solids in liquids

2015

INDEXINDEX Certificate Acknowledgement Aim Introduction Factors affecting diffusion Experiments Conclusion

2015

ACKNOWLEDGEMENTSACKNOWLEDGEMENTS

I would like to express my sincere gratitude to my Chemistry mentor ”Mr. Mehta”, for his vital support, guidance and encouragement - without which this project would not have come forth. I would also like to express my gratitude to the other staffs of the Department of Chemistry for their support during the making of this project.

- KESHAV

AIMAIM

TO STUDY THE DIFFUSSION OF SOLIDS IN LIQUIDS

IntroductionIntroductionWhen substances are brought in contact with each other, they intermingle with each other. This phenomenon is known as Molecular diffusion. Molecular diffusion, often called simply diffusion, is a net transport of molecules from a region of higher concentration to one of lower concentration by random molecular motion. The result of diffusion is a gradual mixing of material. In a phase with uniform temperature, absent external net forces acting on the particles, the diffusion process will eventually result in complete mixing or a state of equilibrium.

Diffusion in the most general state refers to the random, thermal motion of particles. The first thing to remember about diffusion is that all movement is driven by heat energy

Diffusion takes place very rapidly in case of gases, to a lesser extent in case of liquids, and not at all in the case of solids. However, diffusion of solids in liquids does take place at a very slow rate.

Molecules of solute are in constant random motion , called Brownian movement due to the collision between molecules of solute and that of the solvent. It is this physical interaction between solute-solvent particles that leads to diffusion. The atoms (and molecules and other microscopic particles) move every which way, constantly bumping into each other and changing direction

If a solid is kept in contact with excess of solvent in which it is soluble, some portion of the solid gets dissolved. This process is known as dissolution of a solid in liquid.

FACTORS AFFECTING DIFFUSSIONFACTORS AFFECTING DIFFUSSION

Temperature: As temperature increases, the kinetic energy of the particles increases. Thus, the speed of particles also increases, the amount of energy available for diffusion is increased. This means that a given particle will move faster at a higher temperature. Thus the rate of diffusion will be faster as the temperature increases.

Size of the particle: As the size of particle increases, rate of diffusion decreases. The source of energy for the movement of particles in diffusion is the heat in the environment. At a given temperature, a smaller particle (molecule) moves faster than a larger one. Thus the rate of diffusion is inversely proportional to the size of

the particle. That is, a smaller particle will diffuse faster than a larger one.

Mass of the particle: As the mass of the particle increases, the rate of diffusion decreases because the speed of particle decreases and hence the kinetic energy of the particle decreases so the particle becomes less mobile. So as the mass increases the rate of diffusion decreases

Experiment 1Experiment 1AimAim

To study diffusion when copper sulphate isTo study diffusion when copper sulphate is brought in contact with water (liquid).brought in contact with water (liquid).

RequirementsRequirementsCopper sulphate (CuSOCopper sulphate (CuSO44) crystals, 100 mL) crystals, 100 mL beakerbeaker

ProcedureProcedure

Take about two grams of copperTake about two grams of copper sulphate crystals in 100 mL beaker.sulphate crystals in 100 mL beaker.

Add about 50 mL of water and allow itAdd about 50 mL of water and allow it to stand for few minutes.to stand for few minutes.

Note the development of blue Note the development of blue colourcolour in in water.water.

Allow to stand undisturbed further till itAllow to stand undisturbed further till it is observed that all copper sulphateis observed that all copper sulphate disappears.disappears.

Note the blue colour change in water.Note the blue colour change in water.

CONCLUSION -CONCLUSION - When solids such as copperWhen solids such as copper sulphate are brought in contact withsulphate are brought in contact with liquids such as water, diffusion takesliquids such as water, diffusion takes placeplace.

Experiment 2Experiment 2AimAimTo study the effect of temperature on the To study the effect of temperature on the rate of diffusion of solids in liquidsrate of diffusion of solids in liquids..

RequirementsRequirements

Copper sulphate (CuSOCopper sulphate (CuSO44) crystals, three ) crystals, three 100 mL beakers, watch glass, wire gauge, 100 mL beakers, watch glass, wire gauge, burner, tripod stand, thermometer, stop burner, tripod stand, thermometer, stop watchwatch..

ProcedureProcedure

Take five gram of copper sulphate eachTake five gram of copper sulphate each in three beakers.in three beakers.

Pour 100 mL of distilled water slowly inPour 100 mL of distilled water slowly in one of the beakers.one of the beakers.

Cover this beaker with a watch glass.Cover this beaker with a watch glass. Pour 100 mL of cold water in a secondPour 100 mL of cold water in a second

beaker slowly.beaker slowly. Place a third beaker containing 100 mLPlace a third beaker containing 100 mL

of water on a tripod stand for heating.of water on a tripod stand for heating. Observe the diffusion process whichObserve the diffusion process which

begins in all the beakers & record timebegins in all the beakers & record time taken by sol. For dissolution of CuSo4 intaken by sol. For dissolution of CuSo4 in all cases.all cases.

BEAKER Temperature of Water

Time Taken to Diffuse

1 10 °C 18 minutes

2 25 °C 15 minutes3 70 °C 7 minutes

Conclusion:Conclusion: -

The rate of diffusion of copper sulphate inThe rate of diffusion of copper sulphate in water is in the order as given below:water is in the order as given below:

Beaker 3 > Beaker 2 > Beaker 1 Beaker 3 > Beaker 2 > Beaker 1

Faster diffusion will take place if theFaster diffusion will take place if the surroundings are warmer. Increase insurroundings are warmer. Increase in temperature means an increase intemperature means an increase in molecules' speed (kinetic energy). So themolecules' speed (kinetic energy). So the molecules move faster and there will bemolecules move faster and there will be more spontaneous spreading of themore spontaneous spreading of the material which means that diffusion occursmaterial which means that diffusion occurs quicker.quicker.

Experiment 3Experiment 3AimAim

To study the effect of size of particles onTo study the effect of size of particles on the rate of diffusion of solids in liquidsthe rate of diffusion of solids in liquids.

RequirementsRequirements

Graduated 100 mL measuring cylinders,Graduated 100 mL measuring cylinders, copper sulphate (CuSOcopper sulphate (CuSO44) crystals of) crystals of different sizes, stop watch.different sizes, stop watch.

ProcedureProcedure

Add 50 mL of water to each of the threeAdd 50 mL of water to each of the three cylinders.cylinders.

Take five gram each of big size, Take five gram each of big size, medium size, small size crystals ofmedium size, small size crystals of copper sulphate, and add themcopper sulphate, and add them separately .separately .

Allow to them to stand for some time. Allow to them to stand for some time. Note the time taken for blue colour to Note the time taken for blue colour to

reach any fixed mark in each case.reach any fixed mark in each case.BEAKER Crystal size Time Taken to Diffuse

1. Big 19 minutes

2. Medium 13 minutes

3. Small 5 minutes

Conclusion:Conclusion: - Smaller particles have larger Smaller particles have larger surface area. So the small particles of the thirdsurface area. So the small particles of the third beaker interact more with the water the beaker interact more with the water the diffusion hence is fastest in third beaker diffusion hence is fastest in third beaker

Bibliography-Bibliography-

Books:1)Chemistry (Part 1&2) – Textbook for Class XII;

National Council of Educational Research and Training

2) Encyclopedias

Websites:

1) Image Courtesy: www.google.com/images www.wikipedia.org

2) Source and other Information: Wikipedia.org Google.com