I have a school project where I have to make a water-pressure powered bottle rocket (made from 2-liter pop botle). I'm wondering, is there any fuel I could coat the inside of my "rocket" with that would ignite when hit with water? I guess my question is if water ignited propellants exist and how to create some...

oh and by the way, it can't contain any alkali's or dangerous, hard to obtain chemicals.

AFAIK potassium permanganate/aluminium flash powder can be ignited with water and the both chemicals are relatively easy to obtain. However it's also sensitive to friction so it probably isn't suitable for rockets.

http://www.unitednuclear.com/negx.htm

[woot], these however are quite dangerous. I'm afraid that there is no safe chemical, which ignites on contact with water, because this property on its own already is a very unsafe thing .

and certainly Nothing that wouldn`t Melt a Plastic Bottle!

and certainly Nothing that wouldn`t Melt a Plastic Bottle!

 

I was thinking this...lol. Using sodium or somtehing to react with water wouldn't give your rocket a boost anyway.

The only thing I could think of would be a lining of aluminum powder, iodine crystals, and some potssium iodide. When the water hits there would be a reaction between the iodine and aluminum, and the KI would cause any formed iodine to dissolve readily in the water. I'm just not sure how you would get all the I2, Al and KI together without a reaction happening early.

 

As Woelen has already pointed out, something that "explodes" on contact with water is inherently not safe.

I was thinking this...lol. Using sodium or somtehing to react with water wouldn't give your rocket a boost anyway.

 

It would if it forms a gas, so you get ~22.4 L/mole; the expansion would give you propulsion.

but probably not enough propulsion to make a lot of difference. it doesn't have to be totally "safe", as long as I don't die in the process. what I'll probably end up doing is make a sugar rocket and convince my teacher to let met light it off, won't be as cool though...

a pneumatic rocket can be modified to go further, a nossle will do wonders!

but if you really want to make a better one, use hydrogen peroxide (100% if you can get it) and a silver oxide catalyst, it's what makes the bell jetpack fly.

if thats not possible, you can run it on electrolysed water, use the electrolosis to pressurise the bottle and a small spark gap in the air space at the top.

If your trying to create a bottle rocket for SCHOOL, do you really think that water-sensitive chemicals are the best thing to include?

Just get something like alka seltzer tablets. Grind them up, and have them line the inside. Then put some slow disolving material on top of the layer of alka seltzers. Then pump it with water to get some pressure. When you start to notice a reaction going, launch the rocket. I don't think the alcaseltzer will give you a big boost, but it might do something.

How about a mixture of powder citric acid and baking soda underneath a slow dissolving layer? the mixture would create CO2 and the water would mix the acid and the base setting off the reaction that takes place