ALChem energy profile

問題一：

由rate equation睇，一定唔係single stage

如果係single stage既話，X(g) + Y(g) --> XY(g)本身就係rate deterimining step，
寫出黎既rate equation應該係rate=k[X(g)][Y(g)]

如果要寫出rate=k[X(g)][Y(g)]^2，
rate deterimining step一定要係X(g) + 2Y(g) --> product

偶唔記得AL有冇教過，但係rate equation既order = rate deterimining step既reactant coefficient

eg：X --> product rate=k[X]
2X --> product 　　rate=k[X]^2
X + Y --> product 　 rate=k[X][Y]
2X + Y --> product rate=k[X]^2[Y]
2X + 2Y --> product　　rate=k[X]^2[Y]^2

注意左邊既係rate deterimining step，唔係overall equation


問題二：

Possible reaction mechanism可能係
1) 2I-(g) + Ar(g) --> I2Ar(g) Slow（其實係I定I-？）
2) I2Ar(g) --> I2(g) + Ar(g) Fast

其實你可以隨意寫，只要d step加埋得番出條overall equation，
同埋consistent with the rate equation，即係

2I-(g) + Ar(g) --> I2Ar(g)　　　rate=k[I-]^2[Ar]
（2X + Y --> product 　　 rate=k[X]^2[Y]）

Ar應該係intermediate，
energy profile麻煩閣下勞動一下玉手，偶最討厭畫graph……=_=


問題三：

要知係唔係multi-step，請睇rate equation

因為rate = k[A]，所以rate deterimining step係 A --> product
唔match你條overall equation，
所以一定係muti-step

至於energy profile……同上 : )


要判斷既話只要睇rate equation同overall equation match唔match到就得
再唔明可以email問偶，同樣id不過請用hotmail
（yahoo偶十世都唔check……）


PS. 死小電你想同偶Hang幾次機！？同一篇Ans偶打左3次！3次！可．怒．也！+皿+

2008-04-14 10:34:20 補充：
個d "--&gt" 其實係"→"，唔知點解全部亂碼左……=_=

2008-04-14 14:43:01 補充：
更正！
Ar應該係catalyst至啱！

You'd better write down the actual equation and rate equation.

Normally from the rate equation, you could only know which reactant or intermediate involving in the rate determining step. If you compare it with the chemical equation, then you may work out whether it is single or multi step reaction.

If the original reactants appear in the rate equation, we coudl say it is a single step reaction.If intermediate is involved, it must be a multistep reaction.

睇返佢係SN1定係SN2
同埋睇條mechanism本身..

2008-04-10 02:03:46 補充：
你不如講個例子出黎 我先知你邊度唔明=.=
睇到條equation就自然會知 :(

好少何會就咁問嫁下話=.=?
問親呢d都係做exp,有個表,你填哂
跟住用計返個rate equation出黎
自然就會知道邊隻係k[A]^x[B]^y =rate
咁上下既野..
咁你就可以用佢黎support which reactants exist in the rds.

If you know the rate equation of a reaction (if fact, you know the equation of the reaction), you must firstly proposed a mechanism for the reaction before you draw the energy profile. This is because energy profile is the graphical representation for the potential energies of the reactant(s), product(s), intermediate(s) and transition state(s). All these substances are included in the reaction mechanism. You can only draw the energy profile according the mechanism of the reaction.

Furthermore, if the proposed mechanism is incorrect, the corresponding energy profile would become meaningless.