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Postby KDang_1D » Fri Mar 13, 2020 12:10 pm

For homework problem 7A.15, how do you know which experiments to use to calculate the order? For example for A, if you used experiments 1 and 3 instead of experiments 2 and 4, you would get a=3 instead of a=1.

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Re: 7A.15a

Postby nehashetty_2G » Fri Mar 13, 2020 12:28 pm

For A, you have to ensure that only the concentrations for A are changing. Therefore, the concentrations for B must be the same (The concentration of C doesn't matter in this question specifically, so only worry about B). Based on this logic, you can use a combination of experiments such as Rate 2 and 4, but not 1 and 3 since [B] is not kept constant.

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Re: 7A.15a

Postby Uisa_Manumaleuna_3E » Sat Mar 14, 2020 3:09 pm

the above comment is absolutely correct. Always remember that the rates are gonna be different depending on the changing concentrations, so if you look at two concentrations changing at once, you can't really calculate the impact the concentration has on the overall rate change. So if you want to see the impact or order of just one concentration, you need to the two instances in which that concentration is the only thing changing with the rate of reaction.

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Re: 7A.15a

Postby kennedyp » Sat Mar 14, 2020 9:47 pm

I think you have to compare two experiments where everything is constant except for one thing. For example, say for two experiments you have the same concentration of reactant A and B, but reactant C has a different concentration. You would focus on comparing those two experiments.

Bryce Ramirez 1J
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Re: 7A.15a

Postby Bryce Ramirez 1J » Sat Mar 14, 2020 10:19 pm

It is easiest to find two experiments where changes in one of the reactants is equal to an even factor, like 2 or 3. Then you can cross that off from the two combinations of tests required, leaving you with fewer possibilities to choose from for the next tests.

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