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Discussion in 'Science' started by ScienceGuy, Jun 30, 2009.
How did you build them?
Looks a bit fussy but I'll give it a go. (Did the 'whoosh bottle' last week and was very disapointed )
Downloaded a video from the RSC. Some bloke in a white coat and adenoids explains it all.
500ml pop bottle.
Measure the exact volume of the bottle (500ml is actually about 560ml.).
Put 2/3 of the volume of water in the bottle and mark the level.
Fill with water, invert and fill 2/3 full with oxygen. (The bloke in the vid had a cylinder but I used peroxide and MnO2)
Fill remainder of bottle with methane from gas tap and screw down top.
Tried one before school opened. The vid shows it being done indoors so I used the science corridor. 7.45am and the bang from the detonation brought staff from the 4 corners of the building only to find 2 hysterical science teachers and a pop bottle rolling about at the far end of the corridor!
So with the class we filled 8 bottles and took them outside. I had a makeshift launch pad of a bit of plastic guttering taped at a slight slope to a stool.
I had placed a warning notice on the staffroom wall to say that there may be some bangs during lesson 1.
The school field sounded like Bagdhad on a bad day! Hundreds of faces at the windows of the classrooms and members of the SMT running out to see what was happening only to find a class full of hysterical yr 10s and some pop bottles rolling about on the far side of the rounders pitch!
Next week is 'Space day' last session I am going to make more of these with yr 9. Hopefully the grass will be dry and we can get a bit further away from the school buildings. Also I will put a slightly steeper angle on the launch ramp.
However in the lesson we covered Avagadros laws, stoiciometry, Newtons laws, exothermic reactions, energy conversions plus loads of other stuff.
My colleague wants to repeat the experiment using larger bottles! We are looking into it but will need some sort of remote ignition as I am not brave enough to be too close. I have a 3 litre bottle on the shelf!!!
Did the 2 litre bottle survive? I had visions of lttle bits of PET shrapnel whizzing about.
Anyone brave enough to try a water cooler bottle? Perhaps one for Brainiac?
Yeah, the bottle survived, just a bit deformed. I'm sure we used a decent one from carbonated drinks, and not one of the flimsy mineral water bottles.
Wasn't the Brainiac water cooler one a water rocket?? We managed to do it with great effect, you either need lots of energy to pump it up, or do as we did and stole the electric compressor from D&T.
water cooler bottle + ethanol (vapour, so warm a little) + sparking device detailed by prep-room-boy = VERY loud noise and the bottle goes a long way
Doesn't anyone look at their CLEAPSS CDROM? There is a risk assessment for the methane rocket. Among other things, it clearly states that bottles larger than 600ml should not be used.
We do this quite often with 500ml bottles and I would only dare use anything bigger with a remote ignition ( electrical ). I will use a 3 litre outdoors when I get a chance. I reckon it will sound like artillery!
I reckon you could break glass with the detonation!
Middle of an empty playing field with that one I think.
Blazer your department sounds like mine!
The techinican and I made a few the other day to practice them, and fired them from an upside down clamp stand. We also had other members of staff come running as we were creased up with laughter.
We repeated with science club to see if anyone could find the correct ration of oxygen to methane - lots of laughter again amazing!
Correct (Stoiciometric) ratio is 2:1 Oxygen to methane.
ah yes, but the kids had fun trying to work that out! leads nicely into the point of balanced equations.
I've done a similar experiment recently using Hydrogen instead of Oxygen in a similar 2:1 ratio. I used a smaller PET bottle with a remote ignition that our Sci techs rigged up using a car ignition coil to create a spark. Had a bloody big bang and the bottle left a dent in the aluminium support struts in the ceiling! Obviously had the take-off angle a bit too steep.
Would that be Hydrogen instead of Methane?
You are braver than me with the hydrogen. Definite problem with the noise especially indoors. You can cause hearing damage with that one!