Aspects include a valve comprising a flowing liquid, operable to control a flow of gas through a port. Certain aspects include reaction chambers operable to react gases, and in some aspects gases are substantially contained within an envelope comprised of a flowing liquid. Certain embodiments control gas entrance into a chamber with a valve comprised of a flowing liquid controlling gas flow through a port. Various gas scrubbing systems are described, including systems comprising reaction chambers operable to react gases that yield substantial amounts of solid reaction products. Methods for controlling gas flow are disclosed. Systems and methods include sequential steps of wet-scrubbing, reacting and further wet-scrubbing a gas stream.