## 7A.3

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

Mallika Singh 1G
Posts: 99
Joined: Sat Aug 24, 2019 12:16 am

### 7A.3

Ethene is a component of natural gas, and its combustion
has been thoroughly studied. At a certain temperature and pressure, the unique rate of the combustion reaction C2H4(g) + 3 O2(g) --> 2 CO2(g) + 2 H2O(g) is 0.44 mol/Ls
(a) What is the rate at which oxygen reacts? (b) What is the rate of formation of water?

The answer for a) is 1.3, which is what I got. I'm just confused as to why we don't need to include a negative sign? When talking about the unique avg rxn rate formula in the book, it has a negative sign next to the reactants.

Harry Zhang 1B
Posts: 101
Joined: Sat Sep 14, 2019 12:16 am

### Re: 7A.3

Oxygen here is the reactant and therefore its final-initial will be a negative value and the negative sign you see in the unique rate formula takes care of that negative sign and change the rate into a positive one. For the reason of comparing, all rates are considered to be positive in this type of problem.