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### Unique rates

Posted: Fri Mar 01, 2019 3:10 pm
Even though a unique rate is the same for all concentrations of products of reactants, does it still change with time. Therefore can a unique rate at the beginning of the reaction be different than the unique rate at the end since it is a function of time?

### Re: Unique rates

Posted: Fri Mar 01, 2019 8:08 pm
Yes. Unique rate is spontaneous rate, which will definitely change with time. But we usually talk about the initial rate.

### Re: Unique rates

Posted: Fri Mar 01, 2019 8:42 pm
To build off that, we talk about the initial rate of the reactants going to the products only, and not the reverse reaction. This makes our analysis and our calculations nicer.

### Re: Unique rates

Posted: Sat Mar 02, 2019 3:14 pm
Yes, because the unique rate is an instantaneous rate which means it is different at each point in time.

### Re: Unique rates

Posted: Sat Mar 02, 2019 3:38 pm
How do you know when to solve for a unique rate, rather than just a normal instantaneous rate? Is it when there is only one [R] and one [P] on either side of the reaction?

### Re: Unique rates

Posted: Sat Mar 02, 2019 3:55 pm
A unique rate is the rate of appearance/disappearance of a chemical species, divided by the stoichiometric coefficients. The unique rate changes over time as the reaction continues.