chemistry
posted by kiril .
The halflife of a first order reaction is determined to be 92.0 years. How long will it take for the concentration of the reactant to reach 2% of its initial value?

You meant to say the question is: The halflife of a first order reaction is determined to be 85.5 years. How long will it take for the concentration of the reactant to reach 2% of its initial value?

Make use of the formula t=2.303/k*log[Ri/Rf]....where k=0.639/halflyf Rf=2/100Ri..

Got it 519.23512
92.0 years X (multiply) with 5.64386 
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