Rate constants for the gas‐phase reactions of Cl‐atoms with C 2 C 8 alkanes at T = 296 ± 2 K

Relative rate constants for the gas‐phase reactions of Cl‐atom with thirteen atmospherically interesting alkanes (C 2 C 8 ) have been determined at 296 ± 2 K based on GC/FID measurements of their relative decays in the UV (λ ≥ 300 nm) photolysis of mixtures containing Cl 2 and the entire series of the selected alkanes in the mtorr range in 750 torr of N 2 . The following absolute rate constants (in units of 10 −10 cm 3 molecule −1 s −1 ) have been derived from the relative rate constants combined with the value of 1.94 × 10 −10 cm 3 molecule −1 s −1 for the Cl + n ‐butane reaction: ethane (0.57 ± 0.05); propane (1.27 ± 0.02); 2‐methyl propane (1.30 ± 0.01), 2‐methyl butane ((1.96 ± 0.02)), n ‐pentane (2.50 ± 0.02); 2,3‐dimethyl butane (2.00 ± 0.06); 2‐methyl pentane (2.58 ± 0.08); n ‐hexane (3.05 ± 0.04); 2‐methyl hexane (3.12 ± 0.04); n ‐heptane (3.65 ± 0.06); 2,2,4‐trimethyl pentane (2.25 ± 0.08); and n ‐octane (4.09 ± 0.12). The uncertainties indicated are two least‐squares standard deviations (2σ). These rate constants are compared with literature values and their applicability to Arctic tropospheric conditions is discussed. © 1995 John Wiley & Sons, Inc.