What happens to hydrogen gas under pressure ,thats been heated to right below the combustion temperature?
That depends on the pressure and temperature. You see…everything in the universe tends to reach equilibrium. In your case, hydrogen gas under pressure will take liquid forms but still have some molecules of gas form floating above the storing place. If you put more pressure, some of these floating molecules will join their brethren in liquid form so less of the molecules in gas form. Raising temperature means giving energy for molecules to actively bouncing around if it’s gas form or if it’s solid or liquid form just ‘shaking’ there in place. As more and more calories are added, the more energy for bouncing around or ‘shake-shake’ till you break free. So those liquid form of hydrogen gas will start breaking free again into gas form. It’s just a matter of equilibrium between temperature and pressure.
