## Inferring Order

$K = \frac{k_{forward}}{k_{reverse}}$

Abigail Sanders 1E
Posts: 112
Joined: Wed Sep 11, 2019 12:16 am

### Inferring Order

Does anyone know when you can infer reaction order based on the number of molecules in a reaction? For example the reaction A+B --> C+D could be rate=k[A]^2[B] or rate=k[A][B] depending on experimental data provided. But, in reaction mechanisms we assume that the rate law for A+B--> C+D is rate=k[A][B] even when no experimental data is provided.

Riya Sood 4G
Posts: 160
Joined: Sat Aug 24, 2019 12:18 am

### Re: Inferring Order

The only time we can use stoichiometric coefficients to determine the rate law is when the question states that the reaction is an elementary reaction.

If there is no such indication, then the rate law can be determined based on experimental data and comparing trials to see how changing once concentration affects the rate of the reaction.

Tyler Angtuaco 1G
Posts: 130
Joined: Wed Sep 11, 2019 12:16 am

### Re: Inferring Order

You can infer order based on stoichiometric coefficients only during the individual steps of a reaction. You cannot for the overall reaction. For the overall reaction, you would need experimental data and use the method of initial rates.