The reaction A(aq) + B(aq) → Products(aq) was studied, and the following data were obtained: [A]0 (mol/L) [B]0 (mol/L) Initial rate (mol/L•s) 0.080 0.12 6.53×10-3 0.040 0.080 2.18×10-3 0.020 0.060 8.16×10-4 0.16 0.060 6.53×10-3 The rate constant for the reaction without units is ___.