an apparatus is provided to generate a gas by mixing chemicals with water . typically , the production of gas , particularly oxygen , by combining water with powders and other dry chemicals has not been widely employed . there have existed a number of preexisting barriers such as undesirable flow rates and yields . however , by utilizing multiple reaction chambers the flow rates and yields can be more precisely tailored for a variety of situations that may call for particular flow rates and yields . additionally , the use of the dry chemicals would allow for a long self - life allowing the apparatus to be particularly useful in emergency situations .