Question

If the half life of a reaction A is 2 mins,how long will it take A to reach 25% of its initial concentration ?

Answer 1

k = 0.693/2 min = ?. Then subsitute k into the below equation.

ln (Ao/A) = kt
Let Ao = 100, then A = 25. Substitute Ao, A, and k into the equation and solve for t in minutes.