Scenario: Suppose that a pump creates a partial vacuum, which is used to input air (gas) from the environment into a long tube. At a certain point within this tube, diatomic hydrogen and oxygen (gases) are also inputted into the tube. The tube outputs back into the environment. I have provided a diagram that illustrates this. Goal: What is a good theoretical procedure for estimating what portion of the added inputs, hydrogen and oxygen, is transformed into water before being outputted to the environment? Here are my thoughts on what factors to consider: 1. The dimensions of the tube; length, since that sets the time limit in which the gases must react, and diameter, since this determines what region of space the gases are permitted to move in. 2. The amounts of input substances; obvious. 3. Temperature; affects the kinetic energy of the molecules and the rate of reactions. 4. Pressure gradient; I expect that, in general, this would cause a unidirectional flow of the gas molecules and change in the kinetic energy of the molecules, maybe even affecting the rate of the reaction (?) Any advice on the mathematical analysis or additional concepts to consider would be greatly appreciated. Thanks for your time.