## 15.17

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

### 15.17

When we're solving for the order of a reactant in an equation, we usually go about by finding the experiments in the table in which that reactant's concentration changes and where the other reactants are held constant. However, if one of the reactants is independent of the rate, how does this affect our calculations and how we should go about choosing which experiments to work with? For example, in 15.17a, [C] is independent of the rate. Do we then simply ignore the values listed for [C]0? Meaning, when we solve for the order with respect to A, we look for experiments where [B] is held constant? Similarly, when solving for the order with respect to B, we should look for experiments where [A] is held constant? That's how I went about solving the question. Could someone verify if this is conceptually correct?

Rohan Chaudhari- 1K
Posts: 32
Joined: Fri Sep 29, 2017 7:06 am

### Re: 15.17

Yes you are right. Since C is a zero order, its concetration is ignored when determinining the rate of A and B

Dang Lam
Posts: 55
Joined: Thu Jul 27, 2017 3:01 am

### Re: 15.17

Abigail Urbina 1K wrote:When we're solving for the order of a reactant in an equation, we usually go about by finding the experiments in the table in which that reactant's concentration changes and where the other reactants are held constant. However, if one of the reactants is independent of the rate, how does this affect our calculations and how we should go about choosing which experiments to work with? For example, in 15.17a, [C] is independent of the rate. Do we then simply ignore the values listed for [C]0? Meaning, when we solve for the order with respect to A, we look for experiments where [B] is held constant? Similarly, when solving for the order with respect to B, we should look for experiments where [A] is held constant? That's how I went about solving the question. Could someone verify if this is conceptually correct?

Yes after you figured out that [C] is 0 order, you "neglect" all the data coming from concentration C because technically, concentration of C has no effect on the rate.

Jennie Fox 1D
Posts: 66
Joined: Sat Jul 22, 2017 3:01 am

### Re: 15.17

Yes, once C is determined to be zero order, you can ignore the concentrations for C entirely, since it does not have an effect on the reaction rate.

veneziaramirez 3I
Posts: 57
Joined: Fri Sep 29, 2017 7:07 am

### Re: 15.17

How can we tell [C] is zero order?

Ammarah 2H
Posts: 30
Joined: Fri Sep 29, 2017 7:06 am

### Re: 15.17

If you take experiments 1 and 4 to try to solve for the order of C, you'll end up getting (700/400)^n = 1. (n is the order you are solving for). Taking the log of 1 is zero, which is why C has to be zero order!

Merzia Subhan 1L
Posts: 33
Joined: Thu Jul 13, 2017 3:00 am

### Re: 15.17

Since [C] is zero order, it is not listed in the rate law. rate=k[A][B]^2