【正文】 mple There is a reaction : H b O 2 H b O 2+in the blood of lung, it is firstorder in Hb (hemoglobin) and also firstorder in O2, the normal concentration of Hb and O2 are 106 molL1S1,為保持 cHb不變 ， 需輸氧 ， 此時(shí) c（ O2） 應(yīng)高達(dá)多少才行 ？ ?解：由于 Hb及 O2均為一級(jí)反應(yīng) ， 所以 (1) V(HbO2)=k cHb c（ O2） = 106 106 106 = 105 molL 1L1， O2 106 molL1 根據(jù)一級(jí)反應(yīng)方程式： lgC0/C=kt/ 得 102 60/ c= molL1mol1L1mol1 L 1mol1 ?正逆向的反應(yīng) k值不一樣（因正逆向 Ea不同） Rate constant : k (1) k: is only 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 reaction. (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 mol反映了反應(yīng)的本質(zhì)決定著反應(yīng)的速率大小 。L1時(shí)的反應(yīng)速率，故又稱為 比速率 。與反應(yīng)物濃度無關(guān)，與反應(yīng)物本質(zhì)及溫度有關(guān)。 ?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)部結(jié)構(gòu)的變化 優(yōu)缺點(diǎn) The effect of the concentration on the reaction rate The expression of reaction rate is connective with the concentration 表達(dá)式就與濃度直接有關(guān) t a n p r o d u c tr e a c tCCvvtt??? ? ???第三節(jié) 濃度對(duì)化學(xué)反應(yīng)速率的影響 質(zhì)量作用定律與速率方程式 (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)物濃度以計(jì)量系數(shù)為指數(shù)的冪的乘積成正比： aA+bB→dD+eE v = k ca(A) cb(B) 例如 v = k c(NO2) c(CO) N O 2 ( g ) + C O ( g ) N O ( g ) + C O 2 ( g ) The rate law (the law of mass action ) 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 elementary reaction . 質(zhì)量作用定律意義 ?溫度一定時(shí)，增加反應(yīng)物濃度可增大反應(yīng)速率 ?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。放熱反應(yīng) EaEa180。 Ea180。它即可分解為反應(yīng)物，也可形成生成物。mol1 一般化學(xué)反應(yīng)在此范圍 The Ea of a ordinary chemical reaction is in this range (4) Ea 60～ 250KJmol1 反應(yīng)極慢，難察覺 The reaction rate is too slow to be feel. (2) Ea40 KJs 1(min1,h1) p r o d u c tr e a c t a n t ccvvtt??? ? ???(1) Average rate 平均速率 The change in the concentration of reactant or product during a time interval. p r o d u c tr e a c t a n t ccvvtt??? ? ???C h a n g e in th e c o n c e n tr a tio n o f s p e c ie sC h a n g e in tim eV ? The change in the concentration of reactant or product at one specific instant time. 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變化與時(shí)間間隔的比值 r a c t a n t p r o d u c tp r o d u c tr e a c t a n t dcdcvvd t d t? ? ?(2) Instantaneous rate 瞬時(shí)速率 H 2 O 2 ( a q ) H 2 O ( l ) + 12 O 2 ( g )I 2 2 2 20( H O ) d ( H O )l imdtccvtt????? ? ??說明 ?用 反應(yīng)物 表示速率變化時(shí)應(yīng)標(biāo)上 負(fù)號(hào) ,以保證速率為正值 ?當(dāng)反應(yīng)速率穩(wěn)定時(shí) ， 反應(yīng)式中用不同物質(zhì)表示的速率間比值等于反應(yīng)式中各物質(zhì)的系數(shù)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)體系中的哪種化學(xué)物質(zhì)表示而得 化學(xué)反應(yīng)速率的表述之二 反應(yīng)進(jìn)度 ξ： ,0BBBBBnnn???????化學(xué)反應(yīng)速率 p r o d u c tr e a c t a n t11 BBB B B Bdcdcd n d cdvV d t V d t d t d t d t?? ? ? ?? ? ? ? ?＝單位體積內(nèi)反應(yīng)進(jìn)度隨時(shí)間變化率 此時(shí)的 v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) ?例： N2 + 3H2 2NH3 322 d ( N H )d ( N ) d ( H )11d 3 d 2 dcccvt t t? ? ? ? ?aA + bB = cC + dD 1 ( A ) 1 ( B ) 1 ( C) 1 ( D )dc dc dc dcva dt b dt c dt d dt? ? ? ? ? ?第二節(jié) 反應(yīng)機(jī)理 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) A B C reactant product react Elementary reaction 元反應(yīng) ： A overall reaction consists of a sequence of elementary 反應(yīng)組成的化學(xué)反應(yīng)叫做非元反應(yīng) A B Reactants Intermediate product react … End product Multistep mechanisms (posite reaction) 非元反應(yīng)（復(fù)合反應(yīng)） Molecularity of reaction 反應(yīng)分子數(shù) 1SO2Cl2 = SO2 + Cl2 The sum of the stoichiometric 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) 單分子反應(yīng) :If a single molecule is involved, the reaction is said to be unimolecular. H 3 C N C H 3 CCNH 3 C C Nmethyl isonitrile rearrange 1NO2+ 1CO = NO + CO2 2NO + 1H2 = N2O + H2O 2I + 1H2 = 2HI 三分子反應(yīng) :Elementary steps involving the simultaneous collision of three molecules are said to be termolecular reaction 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)） . 2N2O5(g)→ 4NO2 (g)+O2(g) (A) N2O5 → NO3 + NO2 (slow， rate limiting step，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 Reaction mechanism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。 Chemical kiics 化學(xué)動(dòng)力學(xué) ?The area of chemistry that is concerned with the speeds, or rates, at which reactions occur is called chemical kiics 第一節(jié) 化學(xué)反應(yīng)速率的表示方法 Reaction rate 化學(xué)反應(yīng)速率 Definition : The ratio of the 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度的增加量與時(shí)間間隔的比值 Unit: mol 難點(diǎn) ?活化能與活化分子數(shù)對(duì)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)速率方程式及進(jìn)行有關(guān)的計(jì)算。 了解內(nèi)容 ?化學(xué)反應(yīng)速率的基本概念。 ?反應(yīng)級(jí)數(shù)與反應(yīng)分子數(shù)概念。Chapter 8 化學(xué)反應(yīng)速率 Chemical kiics 授課對(duì)象 :10級(jí)藥學(xué)本科 掌握內(nèi)容 ?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(duì)反應(yīng)速率的影響。 ?溫度、濃度、催化劑對(duì)化學(xué)反應(yīng)速率的影響及濃度影響的定量關(guān)系 — 質(zhì)量作用定律、化學(xué)反應(yīng)的溫度因子。一級(jí)反應(yīng)的化學(xué)反應(yīng)速率方程式的計(jì)算。 ?二級(jí)、零級(jí)反應(yīng)的特征 ?均相催化作用的特點(diǎn)。 ?一級(jí)反應(yīng)的有關(guān)計(jì)算。L1 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 Rate limiting step or ratedetermining H2 (g) +I2 (g) =2HI(g) (A) I2 (g) = 2I (quick) (B) H2 (g)+2I (g) = 2HI (g) (slow) （