ln [A]


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605941366
Posts: 83
Joined: Wed Oct 04, 2023 8:23 am

ln [A]

Postby 605941366 » Thu Mar 14, 2024 2:33 pm

Hi,
when we are doing first-order decomposition problems, why is ln[A] divided by ln[A] initial? On the equation sheet, we are given ln[A]=-kt+[A]inital. So to solve for something like final concentration we would have ln[A]/ln[A]inital but I don't understand the math going on here, why woudln't we subtract them, like why is it not ln[A]/ln[A]inital as -kt was added to a inital? Is it a calculus rule?

I understand that ln[A]/ln[A]inital is how the math must be done so please don't say thats just the way we do it.

Marianna 1H
Posts: 52
Joined: Sun Nov 12, 2023 8:27 am

Re: ln [A]

Postby Marianna 1H » Thu Mar 14, 2024 2:35 pm

Hello,
In first-order decomposition problems, we divide the final concentration's natural logarithm by the initial concentration's natural logarithm. This helps us compare how much the concentration changes relative to its starting value over time. It's a simple way to understand the reaction's progress and kinetics.

Anahi Guzman 3L
Posts: 45
Joined: Fri Sep 29, 2023 10:13 am

Re: ln [A]

Postby Anahi Guzman 3L » Thu Mar 14, 2024 2:39 pm

Hi so what if you subtract you would still get the same answer you would just have to take the ln of both the final and initial which is more work compared to ln( [A]/[A]initial)=−kt. Also subtracting logarithms is equivalent to dividing them which is one of the logarithms properties. I hope that helps.


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