This article reviews two approaches to exploring collisions and reacti
ons between gases and liquids. We first describe molecular beam scatte
ring experiments, which reveal the detailed ways in which gas atoms an
d molecules scatter from, accommodate on, and react with low vapor pre
ssure liquids. We then discuss droplet flow tube experiments, which un
cover the kinetics of the uptake of reactive and nonreactive gases in
water and in aqueous solutions. Our goals are to develop simple, predi
ctive rules for describing the fate of gas molecules coming into conta
ct with the surface of liquids.