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### Instantaneous rate of change

Posted: Fri Mar 13, 2020 5:49 pm
Is the equation of the instantaneous rate of change (-d[A]/adt) the same as the differential rate law (K[R]^n)?
If it is then why is it that the differential rate law doesnt have a negative and the instantaneous does?

### Re: Instantaneous rate of change

Posted: Fri Mar 13, 2020 10:13 pm
In the first instance (-d[A]/adt), it measures the rate of the decrease of the reactant, but the second instance (K[R]^n) was determined experimentally. It still shows the reactant decreasing, but this time including the rate constant, K, so that you can write rate as a function of concentration.

### Re: Instantaneous rate of change

Posted: Sat Mar 14, 2020 2:00 am
The instantaneous rate law has a negative because the amount of reactant decreases as the reaction takes place.

### Re: Instantaneous rate of change

Posted: Sat Mar 14, 2020 6:49 am
Also keep in mind that if the rate law contains multiple molecules, you can still find the rate of the reaction in relation to one specific molecule my setting the rate law equal to the instantaenous rate law and solving for your molecule.