The laminar flame speed of a premixed stoichiometric mixture of propane?air at 1 atm and 298 K is 0.4 m/s. Estimate the average reaction rate and the reaction zone thickness. Assume the thermal conductivity of the mixture is 0.026 W/mK at 298 K and increases as a function of T1/2. Assume an appropriate average mixture temperature and ignition temperature.