Problem 15.37

[allyz1F]

This problem asks for the time needed for SO2Cl2 concentration to decrease to 10% of the initial concentration. In the answer it says t= ln(SO2Cl2 initial/SO2Cl2 ) / k is equal to ln10/k. Why is this?

[Joshua Xian 1D]

Since final concentration is 10% of the initial, dividing initial by final would result in 10. Therefore, you get ln(10)/k.

[Lauren Seidl 1D]

Because they divide initial concentration by final concentration, you get a value of 10 in the ln and would therefore set ln(10) = k*t. If you divided final concentration by initial concentration instead, you would get a value of 0.1 in the ln, but you would have to set ln(0.1) = - k*t according to the equation ln[A] = -k*t + ln[A]0. They just flipped it around so that positive k*t = ln([A]0/[A]).

[Shanmitha Arun 1L]

You would do ln(1/0.1) which is the same as ln(10).