• When a mechanism has been investigated in detail, it can be understood on many levels of differing detail. • An additional detail about addition of hydrogen halides to alkenes in non-polar solvents is that additional molecules of hydrogen halide assist the rate-determining proton transfer by hydrogen-bond solvation of the halide ion. • What kinetic order is HI (the value of "x" in the equation below) would HI addition to propene exhibit according to the mechanism above? The predicted kinetic order in HI is . (an integer)