[WhoaItsGuo]

Does gaseous hydrogen and gaseous oxygen burn in the same way as liquid hydrogen and liquid oxygen (assuming the gases are burned at the same rate as the liquids and that there are the same amounts by mass)? For example, would both produce the same specific impulse in a rocket engine (same assumptions)? A link would be appreciated.

[DevaDevil]

link

liquid hydrogen and liquid oxygen have too little energy to react. It would stay a mixture until you added external heat (or if the mixing of the 2 adds heat).

After that it is an exothermic reaction that keeps accelerating, since the heat keeps increasing. However, since reaction rate is dependant on temperature it would take awhile before the reaction speed reached the same level as the room-temperature gas-phase reaction. (assuming the gas-phase reaction starts at room temp.)

I am not a rocket scientist so of what it would do in a rocket I have no clue.
However, in the gas-phase reaction, 3 moles of gas create 2 moles, which would probably be a bad thing for a rocket.
And in extremely low temperatures or high pressures, ice will be formed - making it 3 moles of liquid make 2 moles of ice. Also something I think you'd rather not have in a rocket.
But as said before, I am not a rocket scientist.

[pizza1512]

Does gaseous hydrogen and gaseous oxygen burn in the same way as liquid hydrogen and liquid oxygen (assuming the gases are burned at the same rate as the liquids and that there are the same amounts by mass)? For example, would both produce the same specific impulse in a rocket engine (same assumptions)? A link would be appreciated.

It is quite unclear what you are trying to say...

When gases are burnt at the same rate of liquids i.e. with the same amount of energy, the gas should produce more energy than the liquid.  The liquid firstly would have to required its own energy to react, and would remain as DevaDevil pointed out as a liquid mixture with the oxygen.  Particles in gases already have a high amount of kinetic energy and referencing to the collision theory, there would be a high collision rate.  However the amount of energy that the gas reaction produces is increased dramatically by the pressure put on the gas mixture in the rocket engine.  So if you refer 'specific impulse' to be 'the amount of energy released i.e. the enthalpy of a reaction, then they (the liquid and gaseous states of both reactants) would produce different amounts of energy: the gases produce more energy than the liquids.

[WhoaItsGuo]

Sorry I wasn't that clear, but you answered my question perfectly. Thanks for the link.