15.23?

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Adriana Rangel 1A
Posts: 96
Joined: Fri Sep 29, 2017 7:04 am

15.23?

Postby Adriana Rangel 1A » Sun Mar 04, 2018 1:49 pm

In part C, why isn't [A]t going to be equal to .034? Why do we have to multiply it by two and then subtract that from the concentration of [A] 0 ?

Carlos Gonzales 1H
Posts: 50
Joined: Fri Sep 29, 2017 7:05 am
Been upvoted: 1 time

Re: 15.23?

Postby Carlos Gonzales 1H » Sun Mar 04, 2018 2:22 pm

0.034 is the concentration in terms of B. You have the initial concentration in terms of A so you must convert [B] to [A] using the stoichiometric coefficients.

Sean Monji 2B
Posts: 66
Joined: Fri Sep 29, 2017 7:06 am

Re: 15.23?

Postby Sean Monji 2B » Sun Mar 04, 2018 2:36 pm

Just to clarify, in a reaction where 2A -> B + C, if B is increasing by 0.034 (assuming B initial = 0), then A must decrease by 0.034 * 2 since the reaction requires 2 A to be converted into B. As A initial = .134 and the change in A is -0.034 * 2, A at time t is .134 - 2 * 0.034.
Of course, C can be ignored.
Hope that makes sense

April P 1C
Posts: 38
Joined: Thu Jan 12, 2017 3:01 am

Re: 15.23?

Postby April P 1C » Mon Mar 05, 2018 5:44 pm

On chegg part of the solution is written :

[A] = [A]* - ([B]/2)
[A] = (0.153)- 2(0.034) = 0.085

Why is the first part written as ([B]/2) ?


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