inonickname wrote:SpudBlaster15 wrote:inonickname wrote:Ignoring oxidizer, graphite will yield 72.9 MJ/L, compared to 83.8 MJ/L for aluminium. Comparing the masses of aluminium oxide and CO2, I'd suggest graphite to be a better propellant if you could find a suitable oxidant. Water could even work with the kind of input energies you're dealing with I suppose.
H<sub>2</sub>O + C -> 1.9kJ/g
H2O2 of reasonable concentration would be a good oxidant for either aluminium or carbon. Peroxide watergels make respectable HE's at decent concentrations too. Of course H2O2 distillation can be tricky and unsafe, and you of course have the issues with dangerous materials if you try buy it. There's a world of oxidizers out there that could be made to work though.
The highest concentration I've been able to locate on retail store shelves in this country is 12% H<sub>2</sub>O<sub>2</sub>, sold as 40 volume hair bleach. It's 3:00am, so I may have royally fudged the calculation, but 12%/V hydrogen peroxide/carbon will still be endothermic with an enthalpy change of 0.76kJ/g.
Boiling to concentrate is certainly a possibility, but DYI could always just get my friend SWIM to send him a bottle of his 35% H<sub>2</sub>O<sub>2</sub>. Unfortunately, even 35% H<sub>2</sub>O<sub>2</sub>/carbon isn't going to be very energetic at -1.65kJ/g.
In either case, the oxidizer would probably require distillation to 50%+ to be usable with graphite. Probably not a good idea for someone in DYI's situation to be storing high concentration peroxide anyway.
I managed to get to the sulfate salt, but my yields were poor due to the low concentration or the NaClO I used. I verified it with a silver mirror test with AgNO3. I'm not sure I'm game to do an anhydrous distillation from the salt, even though it's an easy process. I'm sure Spud and DYI understand the hesitation.
Looking forward to seeing some 1kg Astrolite charges in the near future.