## 15.3 C

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

Michelle Dong 1F
Posts: 110
Joined: Fri Sep 29, 2017 7:04 am

### 15.3 C

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

How do you find the unique rate of the reaction? I don't really get what the solutions manual says about this part.

William Xu Dis 1D
Posts: 31
Joined: Fri Sep 29, 2017 7:05 am

### Re: 15.3 C

The unique rate of the reaction is always given by this format (click on the link to see)
https://i.ytimg.com/vi/ycXCSY7N3qc/maxresdefault.jpg

So therefore, according to this equation, because NO2 has a coefficient, it's rate of consumption it must be divided by that coefficient to find the rate of the reaction.
Last edited by William Xu Dis 1D on Fri Mar 02, 2018 8:13 pm, edited 1 time in total.

Tiffany Dao 1A
Posts: 32
Joined: Fri Sep 29, 2017 7:05 am

### Re: 15.3 C

When you calculate the change in concentration over the change in time, you get the rate of 2NO2, but you need the unique rate. This means that they're asking for the rate of one mole of NO2, so you divide the rate by 2.

Cristina Sarmiento 1E
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Joined: Wed Nov 16, 2016 3:02 am

### Re: 15.3 C

The unique reaction rate takes into account the coefficients of the chemical equation.

Ashley Davis 1I
Posts: 57
Joined: Fri Sep 29, 2017 7:04 am

### Re: 15.3 C

The solution manual lists instead of an answer for (c), another answer for (b). And it's solution is +3.3 x 10^-3 instead of -3.3 x 10^-3. Is this another error? Or could someone explain to me why this solution would be positive and not negative, if the formula for unique rate would be -1/a ΔA/Δt.

Chloe1K
Posts: 23
Joined: Fri Sep 29, 2017 7:05 am

### Re: 15.3 C

it's a positive value for b) because when you're finding the rate of the products (formation of O2), it's + 1/c ΔC/Δt.

Abigail Urbina 1K
Posts: 102
Joined: Thu Jul 27, 2017 3:01 am

### Re: 15.3 C

The unique rate of a reaction takes into account the stoichiometric coefficients of a reaction. It is the rate of appearance/disappearance of any species in a reaction divided by its stoichiometric coefficient.

Jessica Wakefield 1H
Posts: 58
Joined: Thu Jul 27, 2017 3:00 am

### Re: 15.3 C

the rate you find for 2NO2 would be the unique rate multiplied by two because there is 2 moles of NO2 so to find the unique rate you would just divide by 2

Magdalena Palavecino 1A
Posts: 54
Joined: Fri Sep 29, 2017 7:04 am

### Re: 15.3 C

All you have to do to change and correct your answer if find the rate PER mole