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.