A question on determine the rate of formation (chemistry)

[Kudo Shinichi]

Homework Statement

For the reaction A-->2B+C, the following data are obtained for [A] as a function of time: t=0min, [A]=0.80M; 8min, 0.60M; 24min, 0.35M; 40min, 0.20M.
Calculate the rate of formation of B at t= 28 min.

The Attempt at a Solution

I have found out that this equation is a first order reaction with equation: y=-0.0345145x-0.2270455
then I plug in the time 28 min into x in this equation and I got the ln=-1.1934515
=exp(-1.1934515)=0.3031730544
the rate for first order of reaction is k* (k=-slope), which is equal to 0.01046386638

I am wondering did I do the problem correctly? because I was told that it is a wrong answer.
any comment or help would be great. Thank you very much.

 

[kava]

Sorry for bumping this, but I am also having the same problem as the OP. I found the k value to be 3.4×10^-2 and the at that time (which is 35 minutes in my case) to be .24M . I am not sure what I am doing wrong, any help would be great.

 

[Blueshift5]

I would like to first commend you for your attempt at solving this problem. Your approach seems reasonable and your calculations appear to be correct. However, I would suggest checking your units to ensure that they are consistent throughout the calculation. Also, it would be helpful to have the full problem statement, including the units for the rate of formation, to provide a more thorough evaluation of your solution. Additionally, I would recommend double-checking your calculations to ensure that there are no errors in your math. If you are still unsure about your answer, I would suggest reaching out to your instructor or a peer for further clarification. Overall, keep up the good work and continue to practice and refine your problem-solving skills.