12songhui第六章化學(xué)反應(yīng)速率

1、化學(xué)反應(yīng)速率化學(xué)反應(yīng)速率chemical kinetics授課對象授課對象:10:10級藥學(xué)本科級藥學(xué)本科有效碰撞、活化分子、活化能的概念及有效碰撞、活化分子、活化能的概念及活化能與活化分子數(shù)對反應(yīng)速率的影響?；罨芘c活化分子數(shù)對反應(yīng)速率的影響。溫度、濃度、催化劑對化學(xué)反應(yīng)速率的溫度、濃度、催化劑對化學(xué)反應(yīng)速率的影響及濃度影響的定量關(guān)系影響及濃度影響的定量關(guān)系質(zhì)量作用質(zhì)量作用定律、化學(xué)反應(yīng)的溫度因子。定律、化學(xué)反應(yīng)的溫度因子。反應(yīng)級數(shù)與反應(yīng)分子數(shù)概念。一級反應(yīng)反應(yīng)級數(shù)與反應(yīng)分子數(shù)概念。一級反應(yīng)的化學(xué)反應(yīng)速率方程式的計(jì)算。的化學(xué)反應(yīng)速率方程式的計(jì)算?；瘜W(xué)反應(yīng)速率的基本概念?；瘜W(xué)反應(yīng)速率的基本概念

2、。二級、零級反應(yīng)的特征二級、零級反應(yīng)的特征均相催化作用的特點(diǎn)。均相催化作用的特點(diǎn)?；罨芘c活化分子數(shù)對反應(yīng)速率的影響活化能與活化分子數(shù)對反應(yīng)速率的影響根據(jù)給出的實(shí)驗(yàn)條件寫出化學(xué)反應(yīng)速率根據(jù)給出的實(shí)驗(yàn)條件寫出化學(xué)反應(yīng)速率方程式及進(jìn)行有關(guān)的計(jì)算。方程式及進(jìn)行有關(guān)的計(jì)算。一級反應(yīng)的有關(guān)計(jì)算。一級反應(yīng)的有關(guān)計(jì)算。the area of chemistry that is concerned with the speeds, or rates, at which reactions occur is called chemical kinetics definition : the ratio of t

3、he amount of decreasing in reactant or the amount of increasing in product to a specific time interval. 一定時(shí)間內(nèi)反應(yīng)物濃度的減少量或生成物濃一定時(shí)間內(nèi)反應(yīng)物濃度的減少量或生成物濃度的增加量與時(shí)間間隔的比值度的增加量與時(shí)間間隔的比值unit: moll-1 s-1(min-1,h-1)productreactant ccvvtt the change in the concentration of reactant or product during a time d

4、uctreactant ccvvtt change in the concentration of specieschange in timev the change in the concentration of reactant or product at one specific instant time. 在反應(yīng)時(shí)在反應(yīng)時(shí)間間隔無限小時(shí)，反應(yīng)物濃度或生成物濃度的間間隔無限小時(shí)，反應(yīng)物濃度或生成物濃度的變化與時(shí)間間隔的比值變化與時(shí)間間隔的比值ractantproductproductreactant dcdcvvdtdth2o2(aq)h2o(l) +12o2(g)i-22220(h o

5、 )d (h o )limdtccvtt 用用反應(yīng)物反應(yīng)物表示速率變化時(shí)應(yīng)標(biāo)上表示速率變化時(shí)應(yīng)標(biāo)上負(fù)號負(fù)號,以保證以保證速率為正值速率為正值當(dāng)反應(yīng)速率穩(wěn)定時(shí)，反應(yīng)式中用不同物質(zhì)表當(dāng)反應(yīng)速率穩(wěn)定時(shí)，反應(yīng)式中用不同物質(zhì)表示的速率間比值等于反應(yīng)式中各物質(zhì)的系數(shù)示的速率間比值等于反應(yīng)式中各物質(zhì)的系數(shù)比比va:vb:vc:vd=a:b:c:d 化學(xué)反應(yīng)速率值必須注明是以反應(yīng)體系中的化學(xué)反應(yīng)速率值必須注明是以反應(yīng)體系中的哪種化學(xué)物質(zhì)表示而得哪種化學(xué)物質(zhì)表示而得,0bbbbbnnnproductreactant11bbbbbbdcdcdndcdvv dtvdtdtdtdt 單位體積內(nèi)反應(yīng)進(jìn)度隨時(shí)間變化率單位

6、體積內(nèi)反應(yīng)進(jìn)度隨時(shí)間變化率此時(shí)的此時(shí)的v v代表整個(gè)化學(xué)反應(yīng)的速率，與反應(yīng)體系代表整個(gè)化學(xué)反應(yīng)的速率，與反應(yīng)體系中選擇何種物質(zhì)表示反應(yīng)速率無關(guān)中選擇何種物質(zhì)表示反應(yīng)速率無關(guān)例： n2 + 3h2 2nh3322d (nh )d (n )d (h )11d3d2dcccvttt aa + bb = cc + dd1(a)1(b)1(c)1(d)dcdcdcdcvadtbdtcdtddt reaction processes occur in a single event or step are called elementary steps.一步就能完成的化學(xué)反應(yīng)一步就能完成的化學(xué)反應(yīng)abcre

7、actantproductreactelementary reaction ： a overall reaction consists of a sequence of elementary reaction.由兩個(gè)或兩個(gè)以上的元由兩個(gè)或兩個(gè)以上的元反應(yīng)組成的化學(xué)反應(yīng)叫做非元反應(yīng)反應(yīng)組成的化學(xué)反應(yīng)叫做非元反應(yīng)abreactantsintermediate productreactend productmultistep mechanisms (composite reaction)非元反應(yīng)（復(fù)合反應(yīng)）非元反應(yīng)（復(fù)合反應(yīng)）1so2cl2 = so2 + cl2the sum of the sto

8、ichiometric coefficient of the reactants in elementary reaction.元反應(yīng)中反應(yīng)物系數(shù)之和稱反應(yīng)分子數(shù)元反應(yīng)中反應(yīng)物系數(shù)之和稱反應(yīng)分子數(shù)單分子反應(yīng)單分子反應(yīng):if a single molecule is involved, the reaction is said to be unimolecular.h3cnch3ccnh3ccnmethyl isonitrile rearrange1no2+ 1co = no + co22no + 1h2 = n2o + h2o 2i + 1h2 = 2hi三分子反應(yīng)三分子反應(yīng): :elemen

9、tary steps involving the simultaneous collision of three molecules are said to be termolecular reaction雙分子反應(yīng)雙分子反應(yīng): :elementary steps involving the collision of two reactant molecules are said to be bimolecular reaction（注意：反應(yīng)分子數(shù)僅適用于元反應(yīng)）（注意：反應(yīng)分子數(shù)僅適用于元反應(yīng)）e.g. 2n2o5(g) 4no2 (g)+o2(g) (a) n2o5 no3 + no2

10、(slow，rate limiting step，速率控制步驟），速率控制步驟）(b) no3 no+o2 (quick)(c) no+no3 2no2 (quick)(a)(b)(c)三步就是該的反應(yīng)機(jī)理三步就是該的反應(yīng)機(jī)理the process by which a reaction occurs is called reaction mechanism . it involve one or more intermediates化學(xué)反應(yīng)進(jìn)行的實(shí)際步驟。即實(shí)化學(xué)反應(yīng)進(jìn)行的實(shí)際步驟。即實(shí)現(xiàn)化學(xué)反應(yīng)的各步元反應(yīng)組合的微觀過程現(xiàn)化學(xué)反應(yīng)的各步元反應(yīng)組合的微觀過程h2 (g) +i2 (g) =2

11、hi(g)(a) i2 (g) = 2i (quick)(b) h2 (g)+2i (g) = 2hi (g) (slow)（ rate limiting step/ rate-determining step）the slowest step in mechanism.在化學(xué)反應(yīng)的實(shí)際步驟中，由許多元反應(yīng)組成，在化學(xué)反應(yīng)的實(shí)際步驟中，由許多元反應(yīng)組成，其中最慢的那步元反應(yīng)限制著整個(gè)復(fù)雜反應(yīng)的其中最慢的那步元反應(yīng)限制著整個(gè)復(fù)雜反應(yīng)的速率大小，這一較慢的元反應(yīng)稱為速率大小，這一較慢的元反應(yīng)稱為速率控制步速率控制步驟驟，簡稱，簡稱速控步驟速控步驟l碰撞理論碰撞理論l活化過渡狀態(tài)理論活化過渡狀態(tài)理論

12、理論碰撞認(rèn)為：化學(xué)反應(yīng)的發(fā)生是反應(yīng)理論碰撞認(rèn)為：化學(xué)反應(yīng)的發(fā)生是反應(yīng)物之間發(fā)生有效碰撞的結(jié)果物之間發(fā)生有效碰撞的結(jié)果1、有效碰撞有效碰撞：能發(fā)生化學(xué)反應(yīng)的碰撞能發(fā)生化學(xué)反應(yīng)的碰撞2、彈性碰撞彈性碰撞：不能發(fā)生化學(xué)反應(yīng)的碰撞不能發(fā)生化學(xué)反應(yīng)的碰撞(a)彈性碰撞彈性碰撞 (b)有效碰撞有效碰撞 反應(yīng)物分子互相接近，發(fā)生碰撞，碰撞后發(fā)生反應(yīng)物分子互相接近，發(fā)生碰撞，碰撞后發(fā)生化學(xué)反應(yīng)化學(xué)反應(yīng)僅有分子間的能量交換，不發(fā)生化學(xué)反應(yīng)僅有分子間的能量交換，不發(fā)生化學(xué)反應(yīng)h2 + i2 hi at room temperature the reaction proceeds very slowly . onl

13、y about 1 in every 1013 collisions produces a reaction effective collision . each molecule undergoes about 1010 collisions per secondfor example (1) the molecules of the reactant must have enough energy. to stretch, bend, and ultimately break bonds, leading to chemical reactions.(1)(1)反應(yīng)物分子要有足夠高的能量反

14、應(yīng)物分子要有足夠高的能量以克服分子或離子外層價(jià)電子云間的排斥力以克服分子或離子外層價(jià)電子云間的排斥力而充分接近，產(chǎn)生電子重排，使舊的化學(xué)鍵而充分接近，產(chǎn)生電子重排，使舊的化學(xué)鍵破裂，而形成新的化學(xué)鍵，即形成新的分子破裂，而形成新的化學(xué)鍵，即形成新的分子(2)the colliding molecules with high energy must have a favorable orientation. (2) 具有高能量的分子間碰撞要有合適方向具有高能量的分子間碰撞要有合適方向 分子在碰撞時(shí)，只有相互反應(yīng)的原子碰分子在碰撞時(shí)，只有相互反應(yīng)的原子碰撞在一起才可能發(fā)生化學(xué)反應(yīng)，才能使分子撞在一

15、起才可能發(fā)生化學(xué)反應(yīng)，才能使分子或離子的反應(yīng)部位間舊鍵破裂，新鍵形成或離子的反應(yīng)部位間舊鍵破裂，新鍵形成co + no2 co2 + noocoono no c ocollisions must occur not only with sufficient energy but also with suitable orientation to cause reaction.activated molecule a molecule which has enough kinetic energy to take part in a reaction.具有較大的動能并能夠具有較大的動能并能夠發(fā)生

16、化學(xué)反應(yīng)的反應(yīng)物分子發(fā)生化學(xué)反應(yīng)的反應(yīng)物分子activation energy ( ea ) the minimum energy of the activated molecule or the minimum energy required to initiate a chemical reaction.活化分子所具有的活化分子所具有的最低能量與反應(yīng)物分子的平均能量之差最低能量與反應(yīng)物分子的平均能量之差e平均平均eea活化分子活化分子動能動能enn(1) ea must be positiveea depends on the nature of the reactant and the

17、route of the reaction.ea is different in different reaction.ea is different in different route of a reaction. (2) ea independ on temperature and concentration. (3) ea，the fraction of activated molecule, the reaction rate .ea2ea1activated moleculeskinetic energyennin a given temperatureea，activated m

18、olecules，v ea，activated molecules，v eaea (1) ea400kjmol-1 反應(yīng)極慢，難察覺反應(yīng)極慢，難察覺the reaction rate is too slow to be feel. (2) ea40 kjmol-1 反應(yīng)極快，反應(yīng)極快，v幾乎測不出來幾乎測不出來the reaction rate is too quick to be measured(3) ea 40400kjmol-1 一般化學(xué)反應(yīng)在此范圍一般化學(xué)反應(yīng)在此范圍 the ea of a ordinary chemical reaction is in this range(4)

19、 ea 60250kjmol-1 大部分反應(yīng)在此范圍大部分反應(yīng)在此范圍 the ea of most of chemical reaction is in this rangez:碰撞頻率碰撞頻率 p:方位因子方位因子 f:能量因子能量因子aertfe有效碰撞頻率總碰撞頻率aertvz p fz p e1.活化分子要按一定的取向發(fā)生碰撞活化分子要按一定的取向發(fā)生碰撞2.發(fā)生碰撞的分子在彼此靠近至剩下幾個(gè)分發(fā)生碰撞的分子在彼此靠近至剩下幾個(gè)分子的距離時(shí)，便引起內(nèi)部結(jié)構(gòu)的變化，即子的距離時(shí)，便引起內(nèi)部結(jié)構(gòu)的變化，即反應(yīng)物分子間的價(jià)電子云發(fā)生相互穿透，反應(yīng)物分子間的價(jià)電子云發(fā)生相互穿透，先被活化成一

20、種高能量的中間過渡狀態(tài)：先被活化成一種高能量的中間過渡狀態(tài)：活化絡(luò)合物活化絡(luò)合物3.活化絡(luò)合物分解成為產(chǎn)物或反應(yīng)物活化絡(luò)合物分解成為產(chǎn)物或反應(yīng)物.the colliding activated molecule must have a favorable orientation.the inner structure of the colliding activated molecules change when they are close to each other at several molecular distance , that is, they form an activate

21、d complex with high energy. .the activated complex decomposed ,it will change into the product or reactant. 活化絡(luò)合物是一種處于過渡狀態(tài)高能物質(zhì)，活化絡(luò)合物是一種處于過渡狀態(tài)高能物質(zhì)，它的價(jià)鍵結(jié)構(gòu)處于它的價(jià)鍵結(jié)構(gòu)處于舊鍵部分?jǐn)嗔?、新鍵部分舊鍵部分?jǐn)嗔?、新鍵部分地形成地形成，反應(yīng)分子的，反應(yīng)分子的動能動能大部分暫時(shí)地轉(zhuǎn)變大部分暫時(shí)地轉(zhuǎn)變?yōu)闉閯菽軇菽艿臓顟B(tài)。它即可分解為反應(yīng)物，也可的狀態(tài)。它即可分解為反應(yīng)物，也可形成生成物。當(dāng)舊鍵削弱，新鍵加強(qiáng)時(shí)，就形成生成物。當(dāng)舊鍵削弱，新鍵加強(qiáng)時(shí)，就可以

22、形成生成物，使整個(gè)體系的勢能降低，可以形成生成物，使整個(gè)體系的勢能降低，而完成反應(yīng)而完成反應(yīng)the activated complex is not a stable molecule, and so it exists for only an instant before flying apart one way or the other. it flies apart because its potential energy is higher than that of either the reactant or the product molecules. give out energ

23、yabsorbenergya |ab |b+aabb2a-b ora-a+b-b分子變化分子變化能量變化能量變化kinetic energypotential energy反應(yīng)進(jìn)程反應(yīng)進(jìn)程reactantactivated complex productor reactantkinetic energyh反應(yīng)進(jìn)程的勢能圖反應(yīng)進(jìn)程的勢能圖a2+b2reactants 2abproductsebebcomplex actived potential energye=h0 exothermic reaction放熱反應(yīng)放熱反應(yīng)h3ccnh3ccnpotential energyh02cdreacti

24、on coordinatepotential energy(b)figure5-7 potential-energy changes during the course of a reaction: (a) exothermic reaction. (b) endothermic reaction.ea eaea 吸熱反應(yīng)吸熱反應(yīng)ea 碰撞理論：簡單的把化學(xué)反應(yīng)看成活化碰撞理論：簡單的把化學(xué)反應(yīng)看成活化分子間碰撞到合適部位即可發(fā)生，未考分子間碰撞到合適部位即可發(fā)生，未考慮分子內(nèi)部結(jié)構(gòu)的變化慮分子內(nèi)部結(jié)構(gòu)的變化活化過渡狀態(tài)理論：考慮反應(yīng)時(shí)分子內(nèi)活化過渡狀態(tài)理論：考慮反應(yīng)時(shí)分子內(nèi)部結(jié)構(gòu)的變化部結(jié)構(gòu)

25、的變化the effect of the concentration on the reaction ratethe expression of reaction rate is connective with the concentration directly.化學(xué)反應(yīng)速率的表達(dá)化學(xué)反應(yīng)速率的表達(dá)式就與濃度直接有關(guān)式就與濃度直接有關(guān)tan productreactccvvtt 1.質(zhì)量作用定律質(zhì)量作用定律(law of mass action) 溫度一定時(shí)，元反應(yīng)的反應(yīng)速率與各反應(yīng)溫度一定時(shí)，元反應(yīng)的反應(yīng)速率與各反應(yīng)物濃度以計(jì)量系數(shù)為指數(shù)的冪的乘積成正物濃度以計(jì)量系數(shù)為指數(shù)的冪的乘積成正比

26、：比：aa+bbdd+ee v = k ca(a) cb(b)例如例如 v = k c(no2) c(co) no2(g)+co(g)no(g)+co2(g) when the temperature is fixed , the rate of a elementary reaction is proportional to the product of the molarity of the reactants , each raised to the power of its stoichiometric coefficient in the equation of the elemen

27、tary reaction .溫度一定時(shí)，增加反應(yīng)物濃度可增大反溫度一定時(shí)，增加反應(yīng)物濃度可增大反應(yīng)速率應(yīng)速率碰撞理論解釋：增加了單位體積內(nèi)活化碰撞理論解釋：增加了單位體積內(nèi)活化分子分?jǐn)?shù)，從而增加了分子間的有效碰分子分?jǐn)?shù)，從而增加了分子間的有效碰撞次數(shù)，因而使反應(yīng)速率增加撞次數(shù)，因而使反應(yīng)速率增加2. 反應(yīng)速率方程式：表示反應(yīng)物濃度與反反應(yīng)速率方程式：表示反應(yīng)物濃度與反應(yīng)速率之間定量關(guān)系的數(shù)學(xué)式稱為反應(yīng)應(yīng)速率之間定量關(guān)系的數(shù)學(xué)式稱為反應(yīng)速率方程式。速率方程式。對元反應(yīng)，根據(jù)質(zhì)量作用定律可直接對元反應(yīng)，根據(jù)質(zhì)量作用定律可直接寫出速率方程式：寫出速率方程式：如上例如上例 v = k c(no2)

28、c(co) 一般地一般地aa+bbdd+ee v = k ca(a) cb(b)反應(yīng)分子數(shù)反應(yīng)分子數(shù) = a+b 對復(fù)合反應(yīng)，速率方程式需由實(shí)驗(yàn)測出對復(fù)合反應(yīng)，速率方程式需由實(shí)驗(yàn)測出如反應(yīng)如反應(yīng)實(shí)驗(yàn)證明實(shí)驗(yàn)證明:v =k c(n2o5)研究表明上述反應(yīng)分研究表明上述反應(yīng)分3步進(jìn)行步進(jìn)行一般地一般地 aa+bbdd+ee v = k cm(a) cn(b)2n2o5(g)4no2(g)+o2(g)3. 反應(yīng)速率常數(shù)反應(yīng)速率常數(shù) (rate constant )反應(yīng)：反應(yīng)： aa+bbdd+ee v = k cm(a) cn(b)k稱為速率常數(shù)。與反應(yīng)物濃度無關(guān)，與反應(yīng)稱為速率常數(shù)。與反應(yīng)物濃度無

29、關(guān)，與反應(yīng)物本質(zhì)及溫度有關(guān)。物本質(zhì)及溫度有關(guān)。 k的物理意義：的物理意義：k在數(shù)值上等于各反應(yīng)物濃度均在數(shù)值上等于各反應(yīng)物濃度均為為1moll-1時(shí)的反應(yīng)速率，故又稱為時(shí)的反應(yīng)速率，故又稱為比速率比速率。即即k= v/ca(a)cb(b)=v/1a1b=v(1)when the temperature is fixed, increasing creactant increases the rate of the reaction.(2) collision theory: increasing the fraction of activated molecule in one volume

30、unit increases the effective collision between the molecules , that will result in increase of the rate of the reaction. 相同條件下，相同條件下，k愈大，表示反應(yīng)的速率愈大。愈大，表示反應(yīng)的速率愈大。反映了反應(yīng)的本質(zhì)決定著反應(yīng)的速率大小反映了反應(yīng)的本質(zhì)決定著反應(yīng)的速率大小。 k的量綱則根據(jù)速率方程式中濃度項(xiàng)上冪次的量綱則根據(jù)速率方程式中濃度項(xiàng)上冪次的不同而不同。的不同而不同。 正逆向的反應(yīng)正逆向的反應(yīng)k值不一樣（因正逆向值不一樣（因正逆向ea不同）不同）(1) k: is o

31、nly dependent on the nature of the reaction and the temperature, is independent on creactant. (2)comparing the rates of different reactions under the same condition, the greater the k, the greater the rate of the reaction, that is to say, the rate of the reaction depends on the nature of the reactio

32、n. (4)for a reversible reaction, different direction of the reaction has different k.(because their ea are different) (3) the number of k amount to the number of rate when the concentration of every reactant is 1 moll-111abababvvkvc c k is called specific rate(1)the rate law only can be applied to e

33、lementary reaction.只有元反應(yīng)，才可利用質(zhì)量作用定律直接寫出速只有元反應(yīng)，才可利用質(zhì)量作用定律直接寫出速率方程式率方程式(2)the rate equation of a non-elementary reaction depends on the results of experiment.對非元反應(yīng)，速率方程式由實(shí)驗(yàn)測定對非元反應(yīng)，速率方程式由實(shí)驗(yàn)測定n2o5no2o2(g)no3no2+(g)(g)n2o5(1)(2)(3)no2+no3+ no2+ o2no3+nono2(overall reaction)(slow, rate-limiting step)(quic

34、k)(quick)52onkcv (3) the concentration of pure solid or pure liquid can be considered as 1.純固態(tài)或純液態(tài)反應(yīng)物的濃度可看作常數(shù)，不純固態(tài)或純液態(tài)反應(yīng)物的濃度可看作常數(shù)，不必寫入速率方程式必寫入速率方程式(4) if the solvent was involved in a reaction in a dilute solution, the concentration of the solvent also can be considered as 1.稀溶液中溶劑參與的化學(xué)反應(yīng)，可認(rèn)為溶劑的稀溶液中

35、溶劑參與的化學(xué)反應(yīng)，可認(rèn)為溶劑的濃度無變化，所以在速率方程式不必標(biāo)出溶劑濃度無變化，所以在速率方程式不必標(biāo)出溶劑項(xiàng)項(xiàng)attention反應(yīng)類型：單分子反應(yīng)、雙分子反應(yīng)、三反應(yīng)類型：單分子反應(yīng)、雙分子反應(yīng)、三分子反應(yīng)分子反應(yīng)反應(yīng)級數(shù)：反應(yīng)速率方程式中各反應(yīng)物濃反應(yīng)級數(shù)：反應(yīng)速率方程式中各反應(yīng)物濃度方次之和度方次之和反應(yīng)：反應(yīng)：aa+bb=cc+dd化學(xué)反應(yīng)速率方程：化學(xué)反應(yīng)速率方程：v=kcx(a)cy(b)反應(yīng)級數(shù)反應(yīng)級數(shù) n=(x+y)反應(yīng)級數(shù)可以是整數(shù)、零、分?jǐn)?shù)或小數(shù)反應(yīng)級數(shù)可以是整數(shù)、零、分?jǐn)?shù)或小數(shù)n can be a integer, zero or fraction even neg

36、ative . it is the sum of the exponents on the concentration terms in the rate equation.aa+bb=cc+ddybxackcv the order of reaction: n=(x+y)若為元反應(yīng)，則化學(xué)反應(yīng)速率方程：若為元反應(yīng)，則化學(xué)反應(yīng)速率方程：v=kc a (a)c b (b)x=a；y=b反應(yīng)級數(shù)反應(yīng)級數(shù)= a+b=反應(yīng)分子數(shù)反應(yīng)分子數(shù)如：如：no2+co=co2+no (元反應(yīng)元反應(yīng))v=kc (co)c (no2)反應(yīng)級數(shù)反應(yīng)級數(shù)=1+1=2反應(yīng)分子數(shù)反應(yīng)分子數(shù)=1+1=2aa+bb=cc+dd

37、if it is a elementary reaction:ababvkc cthe order of the reaction= a+b=molecularity of the reactionx=a；y=be.g：no2+co=co2+no (elementary reaction)2conovkccthe order of the reaction= 1+1=2=molecularity of the reactionreaction mechanism of co+cl2=cocl2 (phosgene)：(1)cl22cl（quick）212clcl k 322cl cl clk

38、(2)cl2+ cl cl3（quick）(3)cl3+cococl2+ cl（slow，rate-limiting step）3clcovk cc322223clco32clclco3232cl1 clcoclcovkcck k cc ck k ck cckcc32cl2 clclck cc2cl1 clck cthe overall reaction order is 1+3/2=2.5反應(yīng)級數(shù)與反應(yīng)分子數(shù)的比較反應(yīng)級數(shù)反應(yīng)分子數(shù)使用范圍任何反應(yīng) 元反應(yīng) 取值 整數(shù)、分?jǐn)?shù)或負(fù)數(shù) 1，2，3與反應(yīng)物系數(shù)和的關(guān)系不一定相等相等 反應(yīng)速率與反應(yīng)物濃度的一次方成正比的反應(yīng) 定積分得：一級反應(yīng)方程式

39、 dcdcvkckdtdtc 00ln ktcktcc ec或0lglg2.303ktcc a first-order reaction is one whose rate depends on the concentration of a single reactant raised to the first power dcdcvkckdtdtc 000ln r lgc- lgc2.303ktcktocc ecktdefinite integraly = mx + blgct0the curve of first-order reactionslope-2.303k(1)(2) k is

40、independent on the concentration. units：time-1 e.g. s-1 , min-1,h-1(3) the half-life ( t1/2) of a reaction is the time required for the concentration of a reactant to drop to one half of its initial value, c1/2=1/2c0 .012012ln 12ln20.693 cktctkk、k的數(shù)值與濃度無關(guān)的數(shù)值與濃度無關(guān) 量綱：量綱：時(shí)間時(shí)間-1 s-1 、 min-1、h-1、半衰期：當(dāng)反應(yīng)

41、物濃度由、半衰期：當(dāng)反應(yīng)物濃度由co 時(shí)所需時(shí)間為半衰期，用時(shí)所需時(shí)間為半衰期，用t1/2表示表示一級反應(yīng)一級反應(yīng): c c0 0 ln = k = kt1/2 t1/2= ln2/k 1/2 1/2cot1/2=0.693/k021c is one whose rate depends on the reactant concentration raised to the second power or on the concentrations of two different reactants each raised to the first power.反應(yīng)速率與反應(yīng)濃度的二次方成正

42、比反應(yīng)速率與反應(yīng)濃度的二次方成正比22 dcdcvkckdtdtc definite integral011 ktccy = mx + b二級反應(yīng)方程式二級反應(yīng)方程式1/ct0slope=k 01interceptcthe curve of second-order reaction(1)(2) k units: lmol-1s-1（ min-1、h-1）(3) half life ( t1/2) ：1201tkc the rate of reaction is independent on the concentration of the reactant.0 dcvkckdt defini

43、te integralc = - kt +coy = mx + b零級反應(yīng)方程零級反應(yīng)方程式式ct0(1)slope= - kthe curve of zero-order reaction(2) kunits: mol l -1s-1（ min-1、h-1）(3) half life ( t1/2) :0122ctk反應(yīng)級數(shù)反應(yīng)級數(shù)一級反應(yīng)一級反應(yīng)二級反應(yīng)二級反應(yīng)零級反應(yīng)零級反應(yīng)方程式方程式lgc =-kt/2.303 +lgc0 1/c = kt +1/c0c = -kt + c0 直線關(guān)系直線關(guān)系lgct1/ctct斜率斜率-k/2.303k-kk單位單位s-1lmol-1s-1moll

44、-1s-1t1/20.693/k1/k c0c0/2korder first-second-zero-equationlgc =-kt/2.303 + lgc01/c=kt+1/c0c=-kt+c0 straightlinelgct1/ctctslope-k/2.303k-kk (unit)s-1lmol-1s-1moll-1s-1t1/20.693/k1/k c0c0/2k反應(yīng)反應(yīng)2n2o5no2+o2服從速率方程式服從速率方程式v=kcn2o5，k=1.6810-2s-1,，如在一個(gè)，如在一個(gè)5.00l的容器中放入的容器中放入2.5mol n2o5，在該溫度下反應(yīng)，在該溫度下反應(yīng)進(jìn)行進(jìn)行1

45、min，問，問n2o5的剩余量及的剩余量及o2的生成量各的生成量各為多少？為多少？解：從速率方程式解：從速率方程式v=kcn2o5知，反應(yīng)符合知，反應(yīng)符合 一級反應(yīng)，且一級反應(yīng)，且c0=2.5/5=0.5moll-1 根據(jù)一級反應(yīng)方程式：根據(jù)一級反應(yīng)方程式：lgc0/c=-kt/2.303 得得lg0.5/c=-1.6810-260/2.303c=0.182 moll-1則知?jiǎng)t知n2o5剩余量剩余量n(n2o5)=cv=0.1825=0.91mol參加反應(yīng)參加反應(yīng)n2o5量量n(n2o5)=2.5-0.91=1.59mol設(shè)設(shè)o2的生成量為的生成量為x，則由反應(yīng)方程式得：，則由反應(yīng)方程式得：2

46、n2o5no2+o2 2 11.59 x生成氧的量：生成氧的量：x=1.59/2=0.795 molk is 1.6810-2s-1. add 2.5mol n2o5 in a container of 5.00 l, please calculate how much n2o5 remained and how much o2 created after 1 min.the rate equation of the reaction:2n2o5no2+o2 is listed below,25 n ovkcaccording to25 n ovkcthe reaction is a firs

47、t-order reaction:02lg-2.3030.51.68 1060lg- 0.182mol/l2.303 cktccc-102.50.5mol l5c assume the amount of o2 is x， 2n2o5no2+o2 2 1 1.59 xx=1.59/2=0.795 moln2o5 remainsn(n2o5)=cv=0.1825=0.91molthe consumption of n2o5n(n2o5)=2.5-0.91=1.59mol 在肺部血液中存在在肺部血液中存在hb+o2 hbo2反應(yīng)，對反應(yīng)，對hb及及o2均為一級反應(yīng)，血中均為一級反應(yīng)，血中hb正常濃

48、度正常濃度8.010-6 moll-1，o2 1.610-6 moll-1,在在37時(shí)，時(shí)，k=2.1106mol-1l-1s-1計(jì)算：（計(jì)算：（1）在肺臟血液中，）在肺臟血液中，hbo2的生成速率的生成速率?（2）在某種疾病中，）在某種疾病中，v(hbo2)=1.110-4 moll-1s-1,為保持為保持chb不變，需輸氧，此時(shí)不變，需輸氧，此時(shí)c（o2）應(yīng)）應(yīng)高達(dá)多少才行高達(dá)多少才行？解：由于解：由于 hb及及o2均為一級反應(yīng)，所以均為一級反應(yīng)，所以(1) v(hbo2)=k chb c（o2） =2.110-68.010-61.610-6 =2.710-5 moll-1s-1(2) c

49、（o2）= v(hbo2)/k chb =1.110-4/2.110-68.010-6 =6.510-6 moll-1there is a reaction :hbo2hbo2+in the blood of lung, it is first-order in hb (hemoglobin) and also first-order in o2, the normal concentration of hb and o2 are 8.010-6 moll-1 and 1.610-6 moll-1 respectively.at 37，k=2.1106mol-1l-1s-1(1) please

50、 calculate how quickly the hbo2 was created in the blood of lung(2) if suffering some kind of disease, v(hbo2)=1.110-4 moll-1s-1 in order to keep chb unchanged,how much the c(o2) is in oxygen therapy.(1) v(hbo2)=k chb c(o2) =2.110-68.010-61.610-6 =2.710-5 moll-1s-1(2) c(o2) = v(hbo2)/k chb =1.110-4/

51、2.110-68.010-6 =6.510-6 moll-1 because it is first order in hb and also in o2unit of k is s-1，first-order reactiont1/2=0.693/k=0.693/1.2410-4=5589.9sit is known that the k of a reaction is 1.2410-4s-1, please calculate its half life.已知已知2，2-偶氮二異丁睛的熱分解反應(yīng)：偶氮二異丁睛的熱分解反應(yīng)：k=1.2410-4s-1,計(jì)算：（計(jì)算：（1）t1/2（2）轉(zhuǎn)化

52、率達(dá)）轉(zhuǎn)化率達(dá)75%時(shí)所需時(shí)間時(shí)所需時(shí)間解：（解：（1）單位為）單位為s-1，則為一級反應(yīng)，則為一級反應(yīng)t1/2=0.693/k=0.693/1.2410-4=5589.9s（2）轉(zhuǎn)化率達(dá)）轉(zhuǎn)化率達(dá)75%時(shí)，反應(yīng)物的濃度時(shí)，反應(yīng)物的濃度c=c0-c075%=0.25c0則由則由lgc=-kt/2.303+lgc0lg0.25c0=-1.2410-4t/2.303+lgc0t=11179.8s溫度對化學(xué)反應(yīng)速率的影響：溫度對化學(xué)反應(yīng)速率的影響：不管是吸熱反應(yīng)還是放熱反應(yīng)，只要溫不管是吸熱反應(yīng)還是放熱反應(yīng)，只要溫度升高，均可使化學(xué)反應(yīng)速率加快度升高，均可使化學(xué)反應(yīng)速率加快 如反應(yīng)如反應(yīng) h2+o2

53、h2o 時(shí)才開始反應(yīng)，時(shí)才開始反應(yīng)， 需天才完全化合，需天才完全化合，時(shí)需小時(shí)，時(shí)需小時(shí)， 時(shí)可瞬時(shí)完全。時(shí)可瞬時(shí)完全。e.g.; h2+o2h2o begin to react finish in 80 days， finish in 2 hours finish in a twinkling no matter the reaction is endothermic or exothermic, its rate increase with increasing temperature.aertkaek is the rate constantea is the activation en

54、ergy r is the gas constant 8.314j/mol-kt is the absolute temperature.a:called the frequency factorlnlnaekart lglg2.303eakart21211 2lnrmkhttkrttut2 t1 時(shí)時(shí) k2 k1 ，反應(yīng)速率，反應(yīng)速率lglg2.303eakartu當(dāng)當(dāng)t一定一定 時(shí)時(shí),lga一定一定,則則ea愈大愈大, k愈小愈小，v愈慢愈慢u對不同的反應(yīng)對不同的反應(yīng),溫度對反應(yīng)速率影響程度不溫度對反應(yīng)速率影響程度不同。當(dāng)同。當(dāng)t相同相同 時(shí)，時(shí)，ea愈大，愈大，斜率斜率ea /t愈大愈大

55、，k的的變化程度愈大變化程度愈大the following table shows the rate constants for the rearrangement of certain reaction at various temperatures.(a)from these data calculate the activation energy for the reaction.(b) what is the value of the rate constant at 430.0k? t/ct/kk 10-51/t10-3lnk189.7462.92.522.160-10.589198

56、.8418-9.855230.3503.56.301.986-7.370251.2507-5.757vant hoff law：k (t+10)： rate constant at (t+10)kt： rate constant at t ：temperature coefficient.for a reaction , t, ； t , when the reactant is fixed, reaction rate increase 2 or 4 times with increasing temperature 10. 42k kt10t：化

57、學(xué)反應(yīng)溫度因子（溫度系數(shù)）：化學(xué)反應(yīng)溫度因子（溫度系數(shù)）同一反應(yīng)同一反應(yīng)在低溫時(shí)在低溫時(shí)較大（溫度對化學(xué)反應(yīng)速率影響較大（溫度對化學(xué)反應(yīng)速率影響程度大）程度大）高溫時(shí)高溫時(shí)較?。ǜ邷貢r(shí)溫度對化學(xué)反應(yīng)速率較小（高溫時(shí)溫度對化學(xué)反應(yīng)速率影響程度小）影響程度?。┩环磻?yīng)，在溫度變化范圍不大時(shí)，同一反應(yīng)，在溫度變化范圍不大時(shí)，變變化很小，對不同反應(yīng)的化很小，對不同反應(yīng)的變化值也不大，變化值也不大，一般為一般為24倍。倍。某反應(yīng)在某反應(yīng)在t時(shí)的化學(xué)反應(yīng)速率為時(shí)的化學(xué)反應(yīng)速率為2moll-1s-1，當(dāng)溫度升高至，當(dāng)溫度升高至(t+40)時(shí)，此時(shí)的化學(xué)反應(yīng)速率有可能為：時(shí)，此時(shí)的化學(xué)反應(yīng)速率有可能為：224

58、 244=32512 moll-1s-1at t, the rate of a reaction is 2moll-1s-1，when the temperature increases to (t+40), how about its rate?its rate will increase to 224 244=32 512 moll-1s-1collision theory: (1) increasing temperature increases the fraction of activated molecules and then increases the rate. (leadi

59、ng reason)(2) increasing temperature increases the kinetic energy of the molecules and then increases the rate. (secondary reason)e.g. the decomposition reaction of n2o5ea=103kjmol-1 at 25 temperature: 2535:fraction of activated molecules: 3.8 timesrate: 3.8 timesaverage kinetic energy of molecules:

60、 only 3.3%.碰撞理論：碰撞理論：溫度升高，使分子獲得更多能量溫度升高，使分子獲得更多能量而成為活化分子。即活化分子分?jǐn)?shù)增加，從而而成為活化分子。即活化分子分?jǐn)?shù)增加，從而使反應(yīng)速率加快使反應(yīng)速率加快(主要影響因素主要影響因素) 溫度升高溫度升高,分子的動能增加分子的動能增加(次要次要影響因素影響因素)氣體分子能量分布曲線：氣體分子能量分布曲線：n n2 2o o5 5分解反應(yīng)的活化能為分解反應(yīng)的活化能為103kj103kjmolmol-1-1溫度溫度:25:2535:35:活化分子百分率活化分子百分率: :3.83.8倍倍反應(yīng)速率反應(yīng)速率v v 3.8 3.8倍倍分子平均動能僅分子平均