Chemistry Project
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Certifcate o authenticity Acknowledgement Acknowledgement Objectie o project "ntroduction #actor$ in%uencing rate o &aporation Application
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&)periment no.!
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Chemistry project
Certifcate o Authenticity This is to certify certify that “Richard “Richard Singh,T” Singh,T” a student of class 12th ‘A’ has successfully completed the research project on the topic “ Rate o Evaporation o Dierent o Dierent Liquids” under the guidance of rs!"ushra! This project project is a#solutely genuine genuine and does not indulge in plagiarism of any $ind! The references references ta$en in ma$ing this project ha%e #een declared at the end of this project!
Signature su!"ect teacher# exa$iner#
Signature
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&hemistry project
Ac%no&'edge$ent( I ee' proud to present $y pro"ect in che$istry on the )Rate o Evaporation o Dierent Liquids”* +his pro"ect &ou'd not have !een easi!'e &ithout the proper rigorous guidance o che$istry teacher ,rs*-ushra &ho guided $e throughout this pro"ect in every possi!'e &ay* An investigatory pro"ect invo'ves various di.cu't 'a! experi$ents/ &hich have to o!tain the o!servations and conc'ude the reports on a $eaningu' note* +hese experi$ents are very critica' and in the t he case o ai'ure $ay resu't in disastrous consequences* +here!y/ I &ou'd 'i%e to than%s !oth ,rs*-ushra and 'a! assistant ,r*'a0ar or guiding $e on a syste$atic !asis and ensuring that in co$p'eted a'' $y experi$ents &ith ease* Rigorous hard &or% has put in this pro"ect to ensure that it proves to !e the !est* I hope that it proves to !e the !est* I hope that this pro"ect &i'' prove to t o !e a !reeding ground or
the next generation o students and &i'' guide the$ in every possi!'e &ay*
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&hemistry project
Rate o Evaporation o Dierent Liquids 1!"ective o the 2ro"ect( (n this project, )e shall in%estigate %arious factors such as nature of li*uid, surface of li*uid and temperature and +nd their correlation correlation )ith the rate of e%aporation e%aporation of dierent li*uids!
Introduction -hen a li*uid is placed in an open %essel, it slo)ly escapes into gaseous phase e%entually lea%ing the %essel empty! This phenomenon is $no)n as %apori.ation or e%aporation! e%aporation! /%aporation of li*uids can #e e0plained in the terms of $inetic molecular model although there are strong molecular attracti%e forces forces )hich hold molecules together! The molecules ha%ing sucient $inetic energy can escape into gaseous phase! (f such molecules happen to come near the surface in a sample of li*uid all the molecules do not ha%e same $inetic energy! There is a small fraction of molecules )hich ha%e enough $inetic
energy to o%ercome the attracti%e forces and escapes into gaseous phase! '
&hemistry project
/%aporation /%aporation causes cooling! This is due to the reason reason that the molecules )hich undergo undergo e%aporation e%aporation ha%e high 3inetic energy therefore the $inetic energy of the molecules )hich are left left #ehind is less! Since the remaining molecules )hich are left ha%e lo)er a%erage $inetic energy! Therefore temperature is $ept constant the remaining li*uid )ill ha%e same distri#ution of the molecular $inetic energy and high molecular energy )ill $ept one escaping from li*uid into gaseous phase of the li*uid is ta$en in an open %essel e%aporation )ill continue until )hole of the li*uid e%aporates! /%aporation /%aporation is an essential part of the )ater cycle! Solar energy dri%es e%aporation of )ater from oceans, la$es, moisture in the soil, and other sources of )ater! (n hydrology, hydrology, e%aporation and transpiration 4)hich in%ol%es e%aporation )ithin plant stomata5 are collecti%ely termed e%apotranspiration! e%apotranspiration! /%aporation is caused )hen )ater is e0posed to air and the li*uid molecules turn into )ater %apour )hich rises up and forms clouds!
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5actors in6uencing rate o Evaporation 1* Concentration o the su!stance evaporating in the air( (f the air already has a high concentration of the su#stance e%aporating, then the gi%en su#stance )ill e%aporate more slo)ly! 2! Concentration o other su!stances in the air( (f the air
is already saturated )ith other su#stances, it can ha%e a lo)er capacity forth su#stance e%aporating! '! +e$perature o the su!stance( (f the su#stance is hotter,
then e%aporation )ill #e faster! ! 5'o& rate o air6 This is in part related related to the concentration concentration
points a#o%e! (f fres (f fresh h air is mo%ing o%er the su#stance all the time, then the concentration of the su#stance in the air is less li$ely li$ely to go up )ith time, thus encouraging faster e%aporation! (n addition, molecules in motion ha%e more energy than those at rest, and so the stronger the 7o) of air, the greater the e%aporating po)er of the air molecules! molecules! 8
9! Inter7$o'ecu'ar orces( The stronger the forces $eeping the
molecules together in the li*uid or solid state the more energy energy that must #e input in order to e%aporate them! 9
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&hemistry project
8! Surace area and te$perature( The rate of of e%aporation e%aporation
of li*uids %aries directly )ith temperature! -ith the increase in the temperature, temperature, fraction of molecules ha%ing sucient $inetic energy to escape out from the surface also increases! Thus )ith the increa increase se in temperature temperature rate rate of e%aporation e%aporation also increases! olecules that escape the surface of the li*uids constitute the e%aporation! Therefore larger surface area contri#utes accelerating e%aporation! e%aporation! :! 9ature o Liquids( The magnitude magnitude of inter;molecular inter;molecular forces forces of
attraction in li*uid determines the speed of e%aporation! -ea$er the inter;molecular forces of attraction larger are the e0tent of e%aporation! (n diethyl ether rate of e%aporation is greater than that of ethyl alcohol!
li*uids depends upon the 7o) of air currents a#o%e the surface of the li*uid! Air current 7o)ing o%er the surface of the li*uid too$ a)ay the molecules of the su#stance in %apour state there#y pre%enting condensation! =! Density( The higher the the density, the slo)er slo)er a li*uid li*uid e%aporates! (n the >S, the ?ational -eather Ser%ice measures the actual rate of e%aporation from a standardi.ed @pan@ open )ater surface outdoors, at %arious locations nation)ide! thers do li$e)ise around the )orld! The >S data is collected and compiled into an annual e%aporation map! The measurements range from under 'B to o%er the12B inches 4',BBB mm5 per year!
2ressure( (n an area of less pressure, e%aporation happens faster #ecause there is less e0ertion on the surface $eeping the molecules from launching themsel%es
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&hemistry project
App'ications( -hen clothes are hung on a laundry line, e%en though the am#ient temperature temperature is #elo) the #oiling point of )ater, )ater e%aporates! This is accelerated #y factors such as lo) humidity, heat 4from the sun5, and )ind! (n a cloth dryer hot air is #lo)n through the clothes, allo)ing )ater to e%aporate %ery rapidly !
+heory( Cor molecules of a li*uid to e%aporate, they must #e located near the surface, #e mo%ing in the proper direction, and ha%e sucient $inetic energy to o%ercome li*uid ;phase intermolecular forces! nly a small proportion of the molecules meet these criteria, so the rate of e%aporation is limited! Since the $inetic energy of a molecule is proportional to its temperature, e%aporation proceeds more *uic$ly at higher temperatures! As the faster;mo%ing molecules escape, the remaining molecules ha%e lo)er a%erage $inetic energy, and the temperature temperature of the li*uid thus decreases! decreases! This phenomenon is also called e%aporati%e cooling! This is )hy e%aporating s)eat cools the human #ody! /%aporation also tends to proceed more *uic$ly )ith higher 7o) rates #et)een the gaseous and li*uid phase and in li*uids )ith higher %apour pressure! Cor e0ample, laundry on a clothes line )ill dry 4#y e%aporation5 more rapidly on a )indy day than on a still day! Three $ey parts to e%aporation are heat, humidity and air mo%ement !
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&hemistry project
Evaporative equi'i!riu$(7
Dapour pressure p ressure of )ater )ate r %s! temperature! :8B Torr Torr E 1 atm!
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&hemistry project
(f e%aporation ta$es ta$es place in a closed %essel, the escaping molecules accumulate as a %apour a#o%e the li*uid! any of the molecules return to the li*uid, )ith returning molecules #ecoming more fre*uent as the density and pressure of the %apour increases! -hen the process of escape and return reaches e*uili#rium, the %apour is said to #e @saturated,@ and no further change in either %apor pressure or density or li*uid temperature )ill occur! Cor a system consisting of %apour and li*uid of a pure su#stance, this e*uili#rium state is directly related to the %apour pressure of the su#stance, as gi%en #y the &lausius;&la peyron relation6
- here P1, P 2 are the %apour pressures at temperatures T 1, 1, T 2 respecti%ely, H %ap is the enthalpy of %apori.ation, %apori.ation, and R is the uni%ersal gas constant! The rate of e%aporation in an op en system is related to the %apour pressure found in a closed system! (f a li*uid is heated, )hen the %apour pressure reaches the am#ient pressure the li*uid )ill #oil! The a#ility for a molecule of a li*uid to e%aporate is largely #ase d on the amount of $inetic energy an indi%idual particle may possess! /%en at lo)er temperatures, temperatures, indi%idual molecules of a li*uid can e%aporate if they ha%e more than the minimum amount of $inetic energy re*uired for %apori.ation! "ut %apori.ation is not only the process of a change of state from li*uid to gas #ut it is also a change of state from a solid to gas! This process process is also also $no)n as su#limation su#limation 4%apori.ation5! 4%apori.ation5!
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&hemistry project
Experi$ent no* : Ai$( To To compare the rates of e%aporation e%aporation of acetone, #en.ene #en.ene and chloroform! Require$ent( Three same same si.e Fetri Fetri dishes of diameter diameter 1B cm, 1B ml! pipettes, stop )atch, acetone #en.ene and chloroform! 2rocedure( 1! &lean and dry all Fetri Fetri dishes and identify identify them as A, " and &! 2! Fipette out of 1B ml! acetone in Fetri Fetri dish @A@ )ith stopper similarly pipette pipette out 1Bml 1B ml of #en.ene and chloroform chloroform in each of Fetri @"@ and @&@! '! Remo%e the co%er plates from all Fetri Fetri dishes and start the stop )atch! ! Get Get the Fetri Fetri dishes remain remain e0posed e0posed for 1B minute! ?o) co%er each of the Fetri dish and note the %olume of remaining material in them!
1!servation( Fetri dishes ar$ed
+i$e( :; $in* < 8;; Sec* Gi*uid Ta$en Ta$en 4D15 ml!
Dolume
remaining 4D25 ml!
Dol! /%ap! DED1ID2
Rate 4DHT5 ml!Hs
A " &
Resu'ts(Rate of e%aporation of Acetone is Rate of e%aporation of "en.ene is Rate of e%aporation of &hloroform &hloroform is
mlHs! mlHs! mlHs!
Conc'usion( +he inter$o'ecu'ar orces o acetone/ !en0ene and ch'oroor$ are in order* Ch'oroor$ = -en0ene = Acetone* :;
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&hemistry project
Experi$ent no* > Ai$( To To study the eect of surface area on the rate of e%aporation e%aporation of diethyl ether! Require$ent( Three Fetri Fetri dishes of diameter diameter 2!9 cm, cm, 9 cm, :!9 :!9 cm! )ith co%er 1B ml! of pipette and stop )atch! 2rocedure( 1!&lean and dry all Fetri dishes and mar$ them as A, " and &! 2!Fipette out of 1B ml! diethyl ether in each of the Fetri dishes A, " and & and co%er them immediately! '!>nco%er all three Fetri Fetri dishes and start the stop )atch! !?ote the remaining %olume after 1B min! %apori.ation of diethyl ether from each Fetri dish!
1!servation( +i$e( :; $in* < 8;; Sec* Fetri dishes ar$ed A
Jiameter of Dolume Ta$en Remaining Dol! F!T!Js! 4ml!5 4ml!5
/%aporated %olume
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Resu'ts( The order order of e%aporation of acetone acetone in three Fetri dishes dishes as Conc'usion( Larger the surace area $ore is evaporation*
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&hemistry project
Experi$ent no* ? Ai$( To To study the eect of temperature temperature on the rate of e%aporation e%aporation of acetone! Require$ent( T)o T)o Fetri Fetri dishes of 9 cm! cm! diameter diameter each stop )atch, 1B ml! pipette, thermometer thermometer and thermostat! 2rocedure( 1!-ash and &lean, dry the Fetri dishes and mar$ them as A, "! 2!Fipette out of 1B ml! of acetone to each of Fetri dishes A and " and co%er them! '!Fut one Fetri dish at room temperature and to the other heat for same time! !?ote the reading!
1!servation( +i$e( :; $in* < 8;; Sec* Fetri dishes
ar$ed
Time Time 4Sec!5
Temperatur Temperature e Dolume olume Ta$en
/%aporated
4in &elsius5
%olume 4ml!5
4ml!5
A "
Resu'ts( The order order of e%aporation of acetone acetone in t)o Fetri Fetri dishes as gi%en gi%en Room Temperature Temperature ;;;;; Keating
Conc'usion( 1!servatio 1!servation n c'ear'y sho&s that the evaporation increases &ith te$perature*
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&hemistry project
Experi$ent no* 3 Ai$( To To study the eect of air current current on the rate of e%aporation e%aporation of acetone! acetone! Require$ent( T)o T)o Fetri Fetri dishes acetone! acetone! 2rocedure( 1!&lean and dry the Fetri dishes and mar$ them as A and "! 2!3eep one dish )here no air current and other under a fast air current! '!?ote the reading!
1!servation( L (nitial Dolume 1B ml! of Acetone *
Fetri dishes &onditions
Time 4S 4Sec!5
ar$ed A
-ith fan
B
%olume /%aporated 4ml!5 1B
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)ithout fan
9B
1B
Resu'ts( The order order of e%aporation of acetone acetone in t)o Fetri Fetri dishes as gi%en gi%en -ith fan ;;;;;; -ithout Can!
Conc'usion( Conc'usion ( +he rate o evaporation o 'iquid increases &ith the increase in rate o 6o& o air current*
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&hemistry project
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