What volume is necessary for hydrogen and oxygen to combine in a 250 ml flask?

Answer 1

The stoichiometric volume ratio for complete combination is approximately 2:1 (it's not PRECISELY 2:1 because neither hydrogen nor oxygen is an ideal gas), so if you want them to combine as completely as possible, 2/3 of that 250 ml should be hydrogen and 1/3 should be oxygen.

You'd do better measuring masses (in which case you want the ratio to be 2.016 parts hydrogen to 15.9994 parts oxygen), but that's a lot harder to do, and going by volume is definitely close enough to give one heck of a bang when you set it off. I saw this done once, using an ordinary party balloon and a candle on the end of a very long stick in a large auditorium, and it literally shook the entire building when it went off.

Answer 2

To determine the volume necessary for hydrogen and oxygen to combine, we need to consider the stoichiometry of the reaction. Hydrogen combines with oxygen in a 2:1 ratio to form water. Therefore, twice the volume of hydrogen is required compared to oxygen. For a 250 ml flask, the volume of hydrogen required would be 166.7 ml, and the volume of oxygen required would be 83.3 ml.