Chemistry

Heyy, okay I have this chemistry assingmnet and its on kinetics, and I got every single one except this one question and I've been trying for over an hour. I know that I'm probably jus tmissing something but everything I've tried doesnt work. Any help is greatly apprecaited. The question is:

A compound decomposes via a first-order reaction. After a period of 932 minutes at 25°C, 25.6% of the compound was found to have decomposed. If 78.2 g of the compound was originally present, what mass would remain after a further 932 minutes?

Thanks in advance

If 25.6% decomposes in the first 932 minutes, I think 25.6% more will decompose in the next 932 minutes. Check my thinking. That would mean 78.2 - 25.6% - 25.6% = about 43 grams.
To confirm that
ln(No/N)=kt
Plug in No = 78.2
N= 78.2 - 25.6% = 58.18
solve for k
t = 932 min.

THEN use the same formula and plug in No = 58.18
solve for N
you know k
t = 932 min.
Should give the same about 43 g.
Let me know if you have problems with this.

Ahhh, see I was thinking the same thing but I was making it more complicated trying to use the equations, and when I did solve for K I seemed to have divded instead of subtracted...that will do it. Thanks alot!

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asked by Tracy

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