A reaction is second order in A with k = 2.42 L/mol/s. If the initial concentration of A is 0.500 mol/L, what is the half-life?

1. The reaction is second order, so use t(1/2) = 1/(k[A]0) and not the first order formula. 2. The product k[A]0 is 2.42 L/mol/s times 0.500 mol/L. 3. That product is 1.21 per second. 4. Taking the reciprocal gives t(1/2) = 0.826 s. 5. The value 1.21 s reports k[A]0 itself without inverting it. 6. The value 0.286 s is 0.693 divided by 2.42, which wrongly applies the first order half-life formula. 7. Because the order is second, this half-life will lengthen as the reaction eats into the concentration. _Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.4 Integrated Rate Laws_