what are the steps in chemical kinetics calculation?

Answer 1

The actual steps are different depending on the type of reaction you are calculating for. Generally, there are only a couple of things you need to know to carry out a chemical kinetics calculation. Concentration of each component of the rate determining step of the reaction, and the time for at least a known portion of the reaction to occur.
Reactions can usually be broken down into several steps. One of these steps will be called the rate-determining step, because it determines the rate at which the overall reaction is capable of occuring. For example, think of a very simple reaction that we can represent as
A ---> D
If we were to examine this reaction very closely, we might find that it really takes three steps that we could represent as:
A ---> B (which hapeens very fast)
B ---> C (which happens very slowly)
and C ---> D (which happens a faster than the previous step)

What this means is that no matter what, the overall reaction of A ---> D can not happen any faster than the rate of the slowest step, which is B ---> C.
If you were to run this reaction (whatever it is) and monitored how much of D is produced in proportion to time, that would tell you how fast the B ---> C reaction is occuring. Because the last step occurs faster, each time a molecule of C is produced it gets converted to D before another molecule of C is produced. Okay so far?
Now, you also need to know the concentrations of at least some of the materials involved in the rate-determining step. Remember that all reactions can go backwards as well as forward. In our example, the rate-determining step is B ---> C, so how fast the reaction occurs will depend on how much of both B and C are present in the reaction mixture. So using the time that you measure, and the concentrations that you measure, you can calculate what is called the "rate constant" for the particular reaction you are studying. Using our example, we know that C becomes D faster than B reacts to form C, so the concentration of C must be equal to the the concentration of D (written as [C] = [D]). Similarly, the [B] = [A], because A is converted to B much faster than the overall reaction actually occurs.
So for this reaction the rate at which D is produced will be a function of time, and the concentrations of A and D. That is,
d[D]/dt = k[A]/[D]
or
rate = k[A]/[D]


Please note, this is a very simple example. In reality, the different steps in a kinetic study can be quite complicated, and it is essential that you know what the rate-determining step is. It is also possible to use relative rates, or to adjust concentrations in such a way that you may not need to know the actual rate constant for a particular reaction. Having said that, most reactions can be represented by one of only three or four actual calculations depending on the nature of the rate-determining step.

Don't be afraid to ask for more help if you need it.

Answer 2

In general it depend on the calculation.

Answer 3

Depends on the problem.