Homework question 15.17


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Emily_Bennett_3C
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Homework question 15.17

Postby Emily_Bennett_3C » Fri Feb 17, 2017 6:36 pm

When solving for each reactant and the overall order of the reaction, how do we know which experiments to use? And once you set up the fraction ex. (20^a)/10, how do you get 2^a=2?
Thank you.

Chem_Mod
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Re: Homework question 15.17

Postby Chem_Mod » Sat Feb 18, 2017 12:03 am

You want to choose 2 experiments where only one of the concentrations differs from the other. In this case, they chose 1 and 4 because the concentrations of A and B are the same, but C differs. Then you can find the rate with respect to C. The next 2 experiments you want to choose should vary with either A or B but not both. In this case, they chose experiments 2 and 4 where [A] varies but [B] is the same for both.

The solutions manual has a typo. The exponent a should apply to the entire fraction 20/10 (same with the (200/100)b ). So, your equation should be (20/10)a = 4/2, and then you simplify to get 2a = 2

Michelle Steinberg2J
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Re: Homework question 15.17

Postby Michelle Steinberg2J » Tue Feb 27, 2018 8:38 pm

For this question, I tried solving for the order of [C] and got stuck. The solutions manual says that "C is independent of the rate." What does this mean?

mhuang 1E
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Re: Homework question 15.17

Postby mhuang 1E » Tue Feb 27, 2018 9:07 pm

Michelle Steinberg2J wrote:For this question, I tried solving for the order of [C] and got stuck. The solutions manual says that "C is independent of the rate." What does this mean?

This means that C is a zero order reaction: it doesn't depend (or is affected) by the rate. When you compare experiments 1 and 4, you can see that although the initial concentrations of A and B are the same, the initial concentration of C is changed. However, the initial rate for both of the rxns are the same. This shows that "C is independent of the rate."


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