In the presence of excess thiocyanate ion, SCN, the following reaction is first order in iron(III) ion,

Question:

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.
Fe3+(aq) + SCN(aq) → Fe(SCN)2+(aq)
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?