Chemistry
posted by Bryan .
What is the value of the rate constant for a reaction in which 75.0 percent of the compound in a given sample decomposes in 80.0 min? Assume first order kinetics. Use the integrated rate law for a first order reaction. Remember at 75 percent reaction, 25 percent of the reactant is left.

ln(No/N) = kt
No = 100 (I assume 100; you can choose ANY convenient number for No, then N = 25% of that.)
N = 25
k = solve for this
t = 80 min.