Chemistry Project Report on
“Rate of Evaporation of Different Liquids”
I, ____________ student of ___________________ is doing project report entitled “Rate of Evaporation of Different Liquids” being submitted to ___________________is an original piece of work done by me.
Objective of the Project
This project is of the rate of evaporation of different liquid, in which we also discuss the factors which affect the rate of liquid.
When liquid is placed in an open vessel. It slowly escapes into gaseous phase ventually leaving the vessel empty. This phenomenon is known as vaporization or evaporation. Evaporation of liquids can be explained in the terms of kinetic molecular model although there are strong molecular attractive forces which hold molecules together. The molecules having sufficient kinetic energy can escape into gaseous phase. If such molecules happen to come near the surface in a sample of liquid all the molecules do not have same kinetic energy. There is a small fraction of molecules which have enough kinetic energy to overcome the attractive forces and escapes into gaseous phase.
Evaporation causes cooling. This is due to the reason that the molecules which undergo evaporation have high kinetic energy therefore the kinetic energy of the molecules which are left behind is less.
Since the remaining molecules which are left have lower average kinetic energy. Therefore temperature is kept constant the remaining liquid will have same distribution of the molecular kinetic energy and high molecular energy will kept one escaping from liquid into gaseous phase of the liquid is taken in an open vessel evaporation will continue until whole of the liquid evaporates.
Factors affecting the rate of evaporation
(1) Nature of Liquids :The magnitude of inter-molecular forces of attraction in liquid determine the speed of evaporation. Weaker the inter-molecular forces of attraction larger is the extent of evaporation. In diethyl ether rate of evaporation is greater than that of ethyl alcohol.
(2) Temperature : The rate of evaporation of liquids varies directly with temperature. With the increase in the temperature, fraction of molecules having sufficient kinetic energy to escape out from the surface also increases. Thus with the increase in temperature rate of evaporation also increases.
(3) Surface Area : Molecules that escape the surface of the liquids constitute the evaporation. Therefore larger surface area contributes accelerating evaporation.
(4) Composition of Environment : The rate of evaporation of liquids depends upon the flow of air currents above the surface of the liquid. Air current flowing over the surface of the liquid took away the molecules of the substance in vapour state there by preventing condensation.
Experiment no. 1
Aim :To compare the rates of evaporation of acetone, benzene and chloroform.
Requirement : Three same size Petri dishes of diameter 10 cm., 10 ml. pipettes, stop watch, acetone benzene and chloroform.
1. Clean and dry all Petri dishes and identify them as A, B and C.
2. Pipette out of 10 ml. acetone in Petri dish "A" with stopper similarly pipette out of 10 ml. of benzene and chloroform in each of Petri "B" and "C".
3. Remove the cover plates from all Petri dishes and start the stop watch.
4. Let the Petri dishes remain exposed for 10 minute. Now cover each of the petri dish and note the volume of remaining material in them.
Time : 10 min. = 600 Sec.
Rate of evaporation of Acetone is 0.0133 ml/s.
Rate of evaporation of Benzene is 0.0166 ml/s.
Rate of evaporation of Chloroform is 0.010 ml/s.
The intermolecular forces of acetone, benzene and chloroform are in order.
Chloroform > Benzene > Acetone.
Experiment no. 2
Aim :To study the effect of surface area on the rate of evaporation of diethylether.
Requirement : Three Petri dishes of diameter 2.5 cm., 5 cm., 7.5 cm. with cover, 10 ml. of pipette and stop watch.
1. Clean and dry all Petri dishes and mark them as A, B and C.
2. Pipette out of 10 ml. diethylether in each of the Petri dishes A, B and C and cover them immediately.
3. Uncover all three Petri dishes and start the stop watch.
4. Note the remaining volume after 10 min. vaporization of diethyl ether from each Petri dish.
Time : 10 min. = 600 Sec.
Results : The order of evaporation of acetone in three petri dishes as 7.5 > 5.0 > 2.5 cm.
Conclusion : Larger the surface area more is evaporation.
Experiment no. 3
Aim :To study the effect of temperature on the rate of evaporation of acetone.
Requirement : Two Petri dishes of 5 cm. diameter each stop watch, 10 ml. pipette, thermometer, thermostat.
1. Wash and Clean, dry the Petri dishes and mark them as A, B.
2. Pipette out of 10 ml. of acetone to each of Petri dishes A and B and cover them.
3. Put one Petri dish at room temperature and to the other heat for same time.
4. Note the reading.
Time : 10 min. = 600 Sec.
Results: The order of evaporation of acetone in two Petri dishes as given
Room Temperature < Heating.
Conclusion : Observation clearly shows that the evaporation increases with temperature.
Experiment no. 4
Aim :To study the effect of air current on the rate of evaporation of acetone.
Requirement : Two Petri dishes acetone.
1. Clean and dry the Petri dishes and mark them as A and B.
2. Keep one dish where no air current and other under a fast air current.
3. Note the reading.
Initial Volume 10 ml. of Acetone.
Results : The order of evaporation of acetone in two Petri dishes as given
With fan > Without Fan..
Conclusion : The rate of evaporation of liquid increases with the increase in rate of flow of air current.
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