2017. Riga Stradin s University

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1 2017. Rig Strin s University Thermoynmics et motion: Greek, Ltin lnguges U - Internl Energy; Enthlpy, et content; S Entropy, on chnges (entity): Greek lnguge- en tropos G Free Energy: Gis Energy, freie Energie: Germn lnguge Δ A Stnr het content of ompoun A kj/mol ΔS A Stnr Entropy content of ompoun A kj/mol ΔG A Stnr Gis Energy content of ompoun A kj/mol Δr, ΔSr, ΔGr et, Entropy, Gis Energy chnge in Rection ΔS isperse =-Δr/T het ispersion; ΔS totl =ΔSr+ΔS isperse totl entropy chnge in rection Δr=ΣΔ prouct ΣΔ initil ; ΔSr=ΣΔS prouct ΣΔS initil ; ΔGr=Δr T ΔSr; Boun energy is clculte s ΔS totl T=-ΔGr is negtive Gis Energy chnge in rection 1) positive ΔS totl T>0 if in proucts is lost Free Gis Energy; 2) negtive ΔS totl T<0 if Energy ccumulte in rection proucts ompoun A hemicl Potentil µ A per one mol s if Δn A =1 mol µ A = ΔG A /Δn A =ΔG A + R T ln(x A ) ; kj/mol with B,, D in mixture 0<X A < 1 lwys is negtive vlue of ln(x A )<0 oncentrtion Expression X A =n A /n totl Mole frction Rection Equilirium onstnt K eq = X c X D XB is constnt vlue in Equilirium mixture ompoun oncentrtions X, XD, XA, XB. Free Energy chnge in Equilirium forms minimum. It s forming Σ prouct Σ initil ifference zero 0=ΔG r+r T ln(k eq ) s well Stnr Free Energy chnge one clcultes with negtive nturl logrithm t equilirium K eq : ΔG r= R T ln(k eq ). Free Energy hnge if not equilirium s humn omeostsis istinguish from Zero vlue n oncentrtion Rtio not onstnt s well: ΔGr=ΔG r+r T ln X c XD XB X c XD XB 0 not zero; 1

2 2017. Rig Strin s University Aris Kksis hemicl potentil n Process Spontneous Direction in omeostsis hemicl potentil show, how much chnge of free energy G A rings into system-rection ing of 1 mole mount of compoun A. In fct: how gret mount of free energy elongs to one 1 mol in mixture. It mens how much free energy G A hs itself per 1 mole compoun A, if mount of compoun in molr numers is n A = 1 mole : µ A = G A n A = G A + R T ln(x A ) (1-1) chemicl potentil of compoun A, where: G A, kj/mol - stnr chemicl potentil t stnr conitions T = K, pressure p = kp; R = J/mol/K - universl gs constnt; ln(x A ) - nturl logrithmic function from rgument X A n X A, unless - molr frction concentrtion of compoun A, expresse s X A = n A /n totl n lying etween 0<X A 1 (sence n pure) compoun A concentrtions, where n A, mol - numer of moles for compoun A n n totl, mol - totl numer of moles ll present compouns totl incluing wter. Logrithmic function properties ln(1) = 0 yiel tht stnr chemicl potentil G A = µ A t X A = 1 is pure A compoun 1 mol free energy content G A, ssuming stnr free energy of formtion G A from elements for compoun A per one 1 mole. Rection procees completely forwr until en only when proucts of rection hve hrly little isposition to reverse chnge ck into rectnts. In other wors these proucts of rection hve trifling remrkle or zero vlue of chemicl potentil: µ proucts = 0, ffinity turns ck to rectnts: A x proucts. Thermoynmics conitions of chemicl equilirium n omeostsis Provie chemicl potentil of rection proucts is tking into consiertion (it hs nything remrkle level of vlue ), then rection procees not completely until en, go not on completely 100% to rectnts conversion to proucts, ut one cn oserve the setting in equilirium. In stte of equilirium sum of chemicl potentils for initil compouns is equl to sum of chemicl potentils for proucts ccoring chemicl rection eqution rectnts A + B n proucts c + D: A + B irect revers c + D ; µ rectnt = µ prouct ; A + B = c + D (1-2) G A+B +D equilirium rection ecuse compoun fctorils,, c, n times µ. For compoun A (A+A+A+)= A=> A times. For compouns B,, n D s seen on eqution of rection expression(1-2), tkes prt times, c n : (B+B+B+)= B=> B ; (+++)= c=> c ; (D+D+D+)= D=> D hemicl potentil µ like s mount of compoun n in mols hve itive properties, e.g. summing. The concentrtions X of rectnts n proucts t equilirium efine the equilirium constnt, Keq (see the hemicl Equilirium). In the +D generl rection chemicl potentil sum for rectnts µ rectnt n proucts µ prouct t equilirium re equl n free energy chnge for A+B 100% 50% 0% 0% +D 100% rection is zero 0 = G rect = µ prouct - µ rectnt n expresse negtive stnr free energy chnge is -G rect = R T ln X c X D =R T ln(k eq ); K eq = X c X D XB (1-3) XB Aris Kksis Rig Strin s University G rect =G rect + R T ln c X XD XB 0; t equilirium zero Grect =G rect +R T ln(k eq )=0 (1-4), in omeostsis (XD X c )/(XA XB ) K eq iffers from equilirium constnt K eq = X c X D XB We must e creful to istinguish etween two 2 ifferent quntities: the free-energy chnge, G, n the stnr free-energy chnge, G. Ech chemicl rection hs chrcteristic stnr free-energy chnge per one 1 mol of rectnt, which mye positive G >0, negtive G <0, or some time zero G =0, epening on the equilirium constnt K eq of the rection. 2

3 2017. Rig Strin s University The stnr free-energy chnge G tells us in which irection n how fr given rection must go to rech equilirium when the temperture is 25 s T o = K, n the pressure p is kp (1 tm) n component concentrtions t equilirium re X. Thus G is constnt: it hs chrcteristic, unchnging vlue for given rection. But the ctul free-energy chnge, G, is function of rectnt n prouct concentrtions X n of the temperture T = K previling uring the rection in humn oy, which will not necessrily mtch the stnr conitions s efine ove. Moreover, the G of ny rection proceeing spontneously towr its equilirium stte is lwys negtive G<0, ecomes less negtive s the reverse rection procees, n is zero G=0 t the point of equilirium (XD X c )/(XA XB ) = K eq, inicting tht no more work W = - G rect = 0 cn e one y the rection: A + B = c + D ccoring expression (1-4) G rect = G rect +R T ln(k eq )=0. Stuies in Meicl chemistry, Biochemistry. Stuies of Gis free energy chnge ΔG rec = Δ rec T ΔS rec Δ rec Enthlpy Disperse energy oun in surrouning n is lost s use free energy ΔG rec <0 1. Enothermic Positive Δ rec >0 2. Exothermic Negtive Δ rec <0 Living cell prolifertions n existing conitions for Life 3. Enothermic Positive Δ rec >0 4. Exothermic Negtive Δ rec <0 ΔS rec Entropy T ΔS rec >0 is ΔS rec >0 Positive entropy increses entropy chnge is positive Disperse energy is forming greter mesure of chos ΔS rec >0 Positive. Spontneous ctolic rections consume free energy chnge ΔG rec <0 for life mintennces of orgnisms 37º in humn s well s to supply the het for orgnisms. ΔS rec <0 Negtive entropy ecreses entropy chnge is negtive Synthesize s well s prouce free energy ΔG rec >0 Positive ccumultes in photosynthesis, in ATP synthesis, in polypepties s well s in proteins, in synthesize molecules, living cells live n prolifertes T Temperture ecomposition rection low T Δ rec > -T ΔS rec high T Δ rec< -T ΔS rec ny T synthesis rection 3 ΔG rec Free energy Biochemicl AB A + B Positive ΔG rec >0 Δ rec T ΔS rec >0 Negtive ΔG rec <0 Δ rec T ΔS rec <0 Negtive ΔG rec <0 Δ rec T ΔS rec <0 Biochemicl no n orgnize in A + B AB ny T Positive ΔG rec >0 high T Δ rec < -T ΔS rec low T Δ rec > -T ΔS rec Δ rec T ΔS rec >0 Positive ΔG rec >0 Δ rec T ΔS rec >0 Negtive ΔG rec <0 Δ rec T ΔS rec <0 Spontneous ility of rection ctolism orgnisms consume the free energy in spontneous rections mintin orgnisms living in omeostsis. unfvorle rection t low temperture spontneous rection t high temperture thermoynmiclly spontneous rection t ny temperture lism energy ccumultes compouns s synthesize the higher orer ecreses mesure of chos ΔS rec <0 negtive unfvorle rection thermoynmiclly forien t ny temperture unfvorle rection t high temperture spontneous rection t low temperture

4 2017. Rig Strin s University In life importnt re negtive chnge ΔS rec <0 of entropy n positive increse ΔG rec >0 of free energy! Negtive chnge ΔS rec <0 isperse energy TΔS ecreses n into rection ccumultes supplie +Q energy into compoun mcroergic ons s increse the free energy ΔG rec >0. Δ rec =ΔG rec + T ΔS rec. pposite to spontneous rection ΔG rec >0 negtive chnge of free energy is lost energy. A.Kksis Rig Strin s University 4 th pge Three Rection exmples stuies of omeostsis for stuents Meicl hemistry : 1. Glucose n oxygen Green plnts Photosynthesis omeostsis re n lue light photons energy E=hν sorption het n free energy ccumultes in glucose n oxygen n sustnce positive Δ rec >0 = -Q Enothermic Δ rec = +2805,27 kj / mol Q + G rection photosynthetic process is Enoergic ΔG r =+3040 kj/mol free energy ccumultes in 1 mol cytosolic glucose molecules iochemiclly in glycolise n Kres cycle mitochonri - comuste y oxygen 2 to comustion proucts 3 ( 2qu ) n 2 long oxitive phosphoriltion pthwy. irect rection E=h PR light re lue photo synthesis comustion reverse rection Glycolysis, xitive Phosphoryltion Plnt Enzymes Photo synthetic Rection enter glucose + oxygen iochemicl comustion Kres cycle in mitochonri The Memrne potentil 3 r pge (pge ATPse riven ATP synthesis (ATP enosine tr ne mole of glucose prouces glycolyticl, mitochonril totlly 36 ATP molecules. Memrne integrl enzyme ATPse nno engine to trnsfer free energy ΔG rec =+30.5 kj/mol for Riosome Enzyme omplex per prouce ATP molecule uner proton grient rives in to Riosome rection energy ADP P 4 - iphosphte ATP 4- nion p=7.36) [ + ] 2290 Proton grient over 1 [ + ] [ + ]=10-5 mol/liter [ + ]= mol/l p=5 + ATPse p=7.36 inter memrne spcee mitochonri ATP Riosome Enzyme omplex ofctor ATP 4-3. For free energy ΔG rec =+17.2 kj/mol trnsfer in Peptie Bon Formtion Rection is The Riosoml protein synthesis: l + glyl-gly+ 2. To trnsfer from ATP 4- lierte n store free energy ΔG rec =+17.2 kj/mol per one mole of peptie on. Al [A] Alnine Riosome joint peptie synthesis with ATP hyrolyze: free energy N + 3 Gly [G] Glycine N + + ATP 4- Riosome A DP P 4 peptie on synthesis ATP hyrolyze is spontneous ΔG =-30.5kJ/mol n totl rection sum is spontneous too ΔG rec = = kj/mol ΔG rec <0 negtive ΔG hyrolize = kj/mol llows to store ΔG rec =+17.2 kj/mol free energy in rection per one mole of peptie on 3 N + N AlninoGlycine Al-Gly AG 4

5 2017. Rig Strin s University Biochemistry synthesis n ecomposition rection four types Synthesis n ecomposition (hyrolyse, iooxition) 1. EXTERMI, EXERGI DEMPSITIN REATIN of YDRLYSIS n BIXIDATIN 3r n 4 th pge : xioreuctses E.1 clsses enzymes, s oxitive phosphoryltion summry: qu => Q + G rection ΔG rect = kj / mol ; Δ rect = kj / mol 2n n 3 r pge : E.2 clss egring enzymes yrolses s igestive peptises: glycil-glycine + 2 peptise => glycine + glycine + Q + ΔG rect ΔG rect = kj / mol ; Δ rect = kj / mol This type of rection cn e written in generl wy s: AB => A + B, Δ<0 n ΔS>0 ΔG = Δ - T ΔS < 0, one cn see, tht the first component of it (Δ) is negtive. ΔS itself is positive, ut s there is minus sign efore it, the secon component of it (- T ΔS) is lso negtive. This mens, tht ΔG is lwys negtive for this type of rections.. onclusion: n exothermic ecomposition rection is spontneous t ll conitions. 2. EXTERMI REATINS F SYNTESIS An EXTERMI REATIN F SYNTESIS in generl wy cn e written s: A + B => AB, Δ<0 n ΔS<0 ΔG = Δ - T ΔS the first component Δ of the eqution is negtive, ut the secon one - positive (ΔS is itself negtive, ut there is minus sign efore it). As one of the components is positive, ut the other negtive, the result ΔG cn e negtive, if the negtive component Δ y its solute vlue is greter, thn the positive component (-TΔS): Δ > T ΔS This is possile, if the temperture is low enough humn oy temperture K onclusion: A synthesis rection, tht is exothermic, is spontneous t low enough tempertures. 3. ENDTERMI, EXERGI REATIN F DEMPSITIN An exmple of n enothermic rection of ecomposition in generl form cn e written s: AB => A + B Δ>0 n ΔS>0 ΔG = Δ - T ΔS Thus, the first component (Δ) in the eqution is positive, ut the secon one (-T ΔS) - negtive s entropy chnge itself is positive vlue, ut the minus sign in the eqution turns the secon component of eqution negtive. In such wy, the chnge of Gis s Energy ΔG cn e negtive (n the rection cn e spontneous), if the negtive component is greter, thn the positive one: T ΔS > Δ An enothermic rection of ecomposition occurs spontneously t high enough tempertures. 5

6 2017. Rig Strin s University 4. ENDTERMI, ENDERGI REATIN F SYNTESIS. oxioreuctse clss E.1 enzymes, s for photo synthesis: ΔG rect = kj / mol ; Δ rect = kj / mol Q + G rect => qu st pge : Protein peptie on synthesis hyrolse clss E.2 enzymes, s for Riosomes: glycine + glycine + Q + ΔG rect => glycil-glycine + 2 ; ΔG rect = kj / mol, Δ=60.58 kj / mol 4th pge : This kin of rections cn e generlly expresse s: A + B => AB Δ>0 n ΔS<0 Thus, oth components of ΔG re positive n therefore ΔG is positive t ny temperture. It mens, tht this type of rection cn never e spontneous - in other wors, n enothermic rection of synthesis is thermoynmiclly forien. We cn esily notice, tht cses 1 n 4 n cses 2 n 3 re reverse rections to ech other. Two more conclusions cn e one: 1) If the irect rection is lwys spontneous, the reverse one is forien.(cses 1 n 4 ). 2) If the irect rection is spontneous t high tempertures, the reverse one must e crrie out t low tempertures. 6

Chemistry Department. The Islamic University of Gaza. General Chemistry B.(CHEMB 1301) Time:2 hours الرقم الجامعي... اسم المدرس...

Chemistry Department. The Islamic University of Gaza. General Chemistry B.(CHEMB 1301) Time:2 hours الرقم الجامعي... اسم المدرس... The Islmic University of Gz Chemistry Deprtment Generl Chemistry B.(CHEMB 1301) Time:2 hours 60 اسم الطالب... الرقم الجامعي... اسم المدرس... R = 8.314 J/mol.K, or = 0.0821 L.tm/mol.K Q1- True ( ) or flse(