In the presence of excess thiocyanate ion, scn−, the following reaction is first order in iron(iii) ion, fe3+; the rate constant is 1.27/s what is the half-life in seconds? how many seconds would be required for the initial concentration of fe3+ to decrease to each of the following values: 25.0% left, 12.5% left, 6.25% left, 3.125% left? what is the relationship between these times and the half-life?