Question

If you start with 4.5×10−2 M I2 at this temperature, how much will remain after 2.56 s assuming that the iodine atoms do not recombine to form I2?

Answer 1

I need more data to do this problem. I'm assuming you are referring to a problem of rate law and rate constant. We need to know first the order of reaction, so we can know what expression to use. For what you are putting here the reaction is a reaction of I₂.

Let me tell you how you will do it with the missing data.

Assuming the reaction is order 1, the equation to use is the following:

lnA = lnAo - kt

From here, we don't have the rate constant (k), but once you have it, you only need to replace the value in the expression along with the value of t (2.56 s) and Ao (4.5x10^-2 M), From here, solve for A (at the end, you will need to take exponential function to solve for A).

If the reaction is order 2, then the expression to use is the following:

1/A = 1/Ao + kt

Again, replace all the value given (including k which you don't provide) and solve for A.

Hope this helps