A reaction has a first order rate constant of 6.11x10-5 s-1 at 25C and 0.00221 s-1 at 85oC. What is the value of the rate constant at 63oC?
on a graph of ln(rate constant)vs 1/temp, you get a straight line
ln r= a/Temp + b
so put in for each temp, r and T, and solve for a and b. (two equations, two unknowns).
Then, knowing a and b, solve for the rate constant at the new temp.
Temps in Kelvins, of course.