TBR, Gchem, Kinetics, Passage 3, #20 (pg 231)

[Sammy1024]

20. Why is the initial rate observed in reaction studies?

A. As a reaction proceeds, it slows. The same period in the reaction must be compared to be consistent.
B. As a reaction proceeds, its rate increases. The same period in the reaction must be compared to be consistent.
C. Only the initial rate can be accurately measured.
D. Any rate can be measured, but the initial one is most convenient.

Looking at the table, k (rate constant) is increasing as the temperature increases, so I don't understand why the rate would be decreasing? I picked, B, but the answer is A. Am I supposed to be looking at 1/T or something?

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[DrknoSDN]

If you didn't look at the table, what answer would you pick?
I don't think the table is required or useful for answering this question.

The question isn't actually asking about that study: "[In general,] why is the initial rate observed in [all] reaction studies?

 

[Sammy1024]

So basically, as a reaction proceeds, it slows down because product it being produced, and the second part of A/B makes sense.

 

[DrknoSDN]

Basically, the answer also gives a caveat to (D) that it is technically not wrong, but A is more correct because measuring the same time interval is the real reason (not convenience).

 

[Sammy1024]

Oh wow. I feel so dumb. I think I got too engrossed in the passage.

 

[Sammy1024]

Thank you for your help! :]

 

[DrknoSDN]

Don't feel dumb. One of the things i struggle with the most is ignoring information presented in a passage.
Every time it gives data that seems to have nothing to do with the problem, I always second guess myself thinking that I'm missing something obvious. (and sometimes I am... lol, hard to tell)

 

[Sammy1024]

I think that's the hard part of the MCAT for me. It's hard for me to figure out when i'm supposed to use the passage details or not.