## Problem 15.3

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

Lucia H 2L
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### Problem 15.3

In 20. s, the concentration of nitrogen dioxide, NO2, decreases from 450 mmol/L to 320 mmol/L in the reaction 2 NO2(g) --> 2 NO(g) + O2(g). (a) Determine the rate of reaction of NO2.

How do you know how to calculate rate of reaction if you don't know the order?

Sohini Halder 1G
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### Re: Problem 15.3

You dont need to. You know how much is changing in how many seconds; this gives you the rate.

Shane Simon 2K
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### Re: Problem 15.3

This problem is just referring to the average rate which is delta Concentration / delta Time. So the order of the reaction isn't needed to find the rate. It would just be -(320-450)/20.

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### Re: Problem 15.3

Equations for the rates of reaction are built off of the form $Rate = \Delta Concentration / \Delta Time$. That is why, for example, the differential rate law of a first-order reaction is $-d[A]/dt$. However, the order of reaction is not need for this problem, as you are given the change in concentration and time elapsed to find the average rate of reaction. Therefore, we can solve $\frac{(320 mmol/L - 450 mmol/L)}{20 sec}$ to get our final answer of 6.5 mmol/L*s

DamianW
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Joined: Fri Sep 29, 2017 7:06 am

### Re: Problem 15.3

You don’t need to know the order unless it asks for something st a certain time