Page 1 of 1

### what if

Posted: Mon Mar 11, 2019 7:21 pm
what would the overall rate for the reaction H2 + I2 --> 2HI look like if it was first order?

i know that the second order formula is rate = k[H2][I2], but dont know what to give if it asked for first order.

### Re: what if

Posted: Mon Mar 11, 2019 7:27 pm
It will still be second order since each reactant is first order.

### Re: what if

Posted: Mon Mar 11, 2019 11:02 pm
For each given reaction, there would be only one unique rate law. Thus, the rate law of a reaction cannot sometimes be first order, sometimes second order. In addition, you cannot determine directly from the written reaction what order it is. It can only be determined by experiment.

### Re: what if

Posted: Mon Mar 11, 2019 11:21 pm
You can't just make it first order. The order of a reaction is determined empirically and cannot be changed. However, if you had a reaction that was simply first order the rate law would appear as Rate = k[A]. Also, a second order rate law is rate = k[A]2.