## Self-Test 15.2A

$aR \to bP, Rate = -\frac{1}{a} \frac{d[R]}{dt} = \frac{1}{b}\frac{d[P]}{dt}$

Alex_Wagas_3K
Posts: 16
Joined: Tue Nov 25, 2014 3:00 am

### Self-Test 15.2A

The average rate of the reaction N2(g) + 3 H2(g) --> 2 NH3(g) over a certain period is reported as 1.15 (mmol NH3)*L-1*h-1. (a) What is the average rate over the same period in terms of the consumption of H2? (b) What is the unique average rate?

For part (a), I am unsure of how to go about solving the problem. The answer the textbook gives is 1.72 mmol*L-1*h-1. I am thinking that the average reaction rate would need to be used, but I am not entirely sure how the 1.15 (mmol NH3)*L-1*h-1 given would fit in as well as the fact that no time is given in the problem. Any help is appreciated. Thank you!

204781248
Posts: 22
Joined: Wed Sep 21, 2016 2:55 pm

### Re: Self-Test 15.2A

Time is actually given in the units. Upon second look at the units, you can see that the concentration of NH3 is given in mmol/L h. h = 1 hour. So from the equation we know that the rate of consumption of H2 = Rate of NH3. Taking into consideration the coefficients, you would set the equation up as 1/3*([H2]/1 hr)=1/2*([NH3]/1hr). From here you can just plug in the given information and solve algebraically to get 1.72.

Hope this helps! :)