UKC

Perhaps unwisely I've volunteered to run an 'explosions night' for our village youth club. (10-14 year old) and looking for ideas that will entertain the kids without risking loss of limbs.

Anything suggested is going to have to stand up to scrutiny in a pragmatic but robust risk assessment, but I still feel like there's fun to be had and possibly teach them a little bit of science.

Top of the list are elephant toothpaste (hydrogen peroxide and yeast), exploding watermelon (rubber bands round watermelon) and something vinegar/bicarb of soda based.

Any other ideas? Ideally I would like something where application of flame leads to a bang but the ideas that have popped into my head so far would probably not get past the risk assessment stage.

https://youtu.be/v4FmUiN4pFo?si=-PqnWgjJC4GmWYJE

You may regret teaching them how to make these.

Custard powder, in a biscuit tin, shaken up and a kitchen piezoelectric sparker applied? Should go off quite well.

Custard powder bomb. Extra comedy points because it uses custard.

A teaspoon of custard powder covering the end of a tube. Light a candle next to it. Cover the lot with a large upended tin can. A sharp puff of air through the tube (foot pump is good). The custard power forms a fuel-air mix and the candle ignites it. Think about where the tin is going to land 🙂

When I was at school our chemistry teacher did a demonstration of what happens if you pour water on a chip pan fire. Indoors! I guess that's probably not allowed any more since classrooms are no longer made of asbestos.

"Whoosh bottle"

Best not under a roof or ceiling unless they're high. 

An empty DRY water bottle off the top of a water dispensing machine. The big blue things. 

Take the fancy valve bottle lid off. 

A couple of drops of meths or similar. Rope it round a touch. 

Stand up, stand back and chuck a match in. 

It's not explosive per se but does make a cool noise and if done in the dark looks really pretty. 

I was once a science teacher, we used to do this in class. 

It'll only work once reliably as the bottle after has no oxygen left once it's finished. Obs with a break and a re established bottle it'll go again. 

Gas bubbles can too be fun for something to burn. 

I haven't actually tried this one...

Set up an electrolysis rig and fill a bin bag with hydrogen. Tie it closed, light the tails and let it go.

Outdoors obviously!

Filling test tubes with hydrogen and lighting them is indoor friendly. I think you can do bubbles too.

Lankyman has been bragging about lighting his stinky farts, so I’d get him on stage. 

Edit: I’ve no idea whether it would ‘lead to a bang’, I think people from St Helens do that sort of messy thing. 

Compressed air rocket? Half fill a bottle with water, use a bike pump to pressurise and launch.  You can get proper kits for it but could also bodge a lid together.  I did this recently with scouts and they all got to experiment with how much water they thought was best.

If access to gas is an option, we did one at school many years ago where the teacher filled a 2ltr coke bottle with water and then filled 2/3 methane, 1/3 oxygen (might have been the other way round) and the  putting the lid back on while still under water. Bottle was then taken into the corridor and placed on top of a stool where the lid was removed and a lit taper on the end of a meter stick was applied resulting in the bottle vanishing down the corridor.

I may have been involved in the following:

Ingredients: 

1x large oil drum, open at one end.

2x large paint tins filled with petrol (preferably syphoned from a car belonging to dirty camping miscreants) with the lids snapped down tight.

A wire coat hanger.

A campfire with a couple of planks forming a flat support, as yet unlit.

Method:

Make a small hole in the closed end of the drum, thread the wire coathanger through and suspend the two paint tins full of petrol from the coat hanger. The drum should be vertically aligned with the open side down, so the tins are hanging from the top, inside the drum.

Place the drum, open side down, on the planks which straddle the campfire.

Light the campfire.

Run like hell and wait.

Mentos and Coke is an easy one to do.

The Screaming Jelly Baby was popular on year 5 open days but Mrs J says I can't suggest it. 

Wheely bin full of seived flour or icing sugar is amusing. 

Jk

The exploding colour one with milk, food colouring and a cotton ball or bud soaked in washing up liquid is good. Not remotely dangerous but looks pretty cool. 

https://www.stevespanglerscience.com/lab/experiments/milk-color-explosion/

Lots of variants, blob the food colouring all over the milk and you'll get lots of reactions. 

Potato cannon. Obviously. Easy to make, and a (relatively) safe participation weapon. Google it and live your dreams. 

Glass bottle, small amount of water in the bottom, drop in some dry ice, cap tightly, throw to the other end of the field.

Can of spaghetti hoops, chuck on campfire, retreat a fair distance.

Glass bottle, small amount of water in bottom, cap tightly, put on campfire, retreat a fair distance. If it leaks steam and doesn't blow, DO NOT return to pee on bottle to set it off.

Diesel and Ammonium Nitrate 

Both easily available, and go with a bang.

And there was me quite content with a tin of unopened beans on a campfire. 

You can buy red iron oxide powder and 9-11 micron aluminium powder online from various chemical suppliers, mix them together in a 3:1 ratio and you get thermite, of Brainiac fame. Quite explodey/burny. 

Set up a simple water electrolysis experiment in a small plastic tub with washing up liquid in the water. Allow the bubbles to build up and then light them. As it's a stoichiometric mixture in the bubbles you'll get quite a bang. (Not too many bubbles!). Definitely test outside at home to ensure it's not too much. I saw it done in a washing up bowl in a lecture theatre and I think that would be too big for a safe demonstration. 

In terms of set up I think an old ( non smart) car battery charger would work as the power source. You'd need a couple of graphite rods as electrodes and a bit of something in the water to make it more conductive. 

I believe there is one you can do with a gas stove! 😜

https://www.bbc.co.uk/news/articles/c3gr28ek257o

The centre for life at Newcastle has a really cool electrolysis setup.

A handle cranked 3-phase permanent magnet alternator is rectified in to DC which has two electrodes, each under a separate tube in the water.  You crank and watch them fill with the two gasses, then valves open to a combustion chamber, then a little DC igniter module sparks the chamber and it goes boom.  The ignition chamber is the bottom of a very tall acrylic pipe sealed by a ping pong ball, which rockets skywards with the explosion.

I did this as a kid using one of those catering tins of coffee. Had it the right way up and blew the lid off (using flour). I put a hole in the bottom and threaded rubber tube (stolen from school) through. Custard/flour atomisation was improved by sticking the little funnel from my chemistry set in the end of the tube inside the tin to form a hopper. Light the candle, put the lid on and puff into the tube. Much shrieking from my long suffering mother. 

If you know any cavers then you could scrounge some calcium carbide they use in lamps, mix a few small rocks with water, contain in a sandwich bag or similar, then ignite from a distance. It makes acetylene which burns rapidly and across a wide range of air fuel ratios so you get a lick of smokey flame then a hell of a pop when it goes.

A 3L pop bottle holds a lot of pressurised gas and goes off like thunder IIRC. Just don't!

jk

I think these are technically 'firearms' and as such you're probably breaking the law.

Only when used in a shopping centre or similar. As it happens, when I built mine, I took it to work and a colleague (policeman) used it in the car park, and said he doesn't think it's illegal!

I remember years ago in Chemistry, we were busily working on an experiment with toluene where you had to stop at a certain point in the reaction.

My teacher casually dropped into the lesson that some kids at a neighbouring school hadn't and had carried on to create TNT in the classroom!

Nitrogen Triiodide - surprisingly easy to make. Nearly got expelled from school in sixth year for painting some on a corridor floor just before bell time...

Have done some of these, along the lines of other posts here, but slightly more detail on the hydrogen generation one which worked well.

Get a substantial glass bottle - something which won't crack under a bit if heat. Buy some sodium hydroxide powder from online hobby craft shops (used in soap making). Make up a NaOH solution (water first then powder) into the bottle, this will generate some heat, but modest. Then tear up some aluminium foil into strips and drop into the bottle - these will fizz and are generating hydrogen, quickly put a balloon over neck of bottle and watch it fill until balloon is less than a third full. Tie the balloon off and tape to end of long garden cane, tie a splint to another long garden cane, light it and use to set fire to the balloon- satisfying small explosion.  

Test at home outdoors until you have the right amount of gas generated, the glass bottle neck gets hot so generally only good for two balloons and then cool down.

On elephants toothpaste, I've never found a decent enough concentration of hydrogen peroxide to make it work well - if anyone knows a source, please tell

I once obtained a large can of ..... and we decided to remove a tree stump near our secret camp in the woods.  We duly filled the stump with the above powder, laid a trail all of 2m to where we hunkered down and then lit it.  It was awesome, just like road runner and Tom and Jerry cartoons with a little sparkling flame racing away towards the tree stump.  THEN... great gouts of flame about two metres high for a few seconds like multiple giant sparklers and nothing, total failure.

Roll forward 20 or so year and I'm watching crafty tricks of war and they guy with the big moustache lights a tea spoon of powder which burns with a great big fierce flame.  I've done that, I thought.  He then says, "now watch what happens when I put a helmet on top of the powder", an almighty bang and the helmet went 30m into the air....

At this point I'm thinking I'm lucky to be alive now and of that phrase, the luck that protects children and idiots.

Be careful.

Cheers

Toby

Match rockets?

A mixture of match heads and striking strip crushed up makes a pretty good flash when a flame is applied. Keep the quantities low, use a long splint for lighting and ensure no combustibles nearby and it's pretty safe.

Still doing this when I was in high school 5 years ago! Though given them age of the building it probably was made of asbestos anyway...

It depends on the muzzle energy - a low powered one is fine. Someone made a very powerful one utilising propane as fuel and the police were less happy with that. To be fair to them the thing could should a potato through a 2 inch ply board so maybe they were justified...

Best soaked into those green paper towels found in chemistry labs then distributed onto radiators to dry

Thanks for the suggestions.  They all sound very entertaining.  I'm going to save the riskiest for home sessions with my own kids, but I think the custard powder bomb and possibly the hydrogen balloon have potential for youth club.

One cautionary tale - one morning we woke up to find our small village crawling with police, some of them armed.  Turns out that a chap who lives in the village had ordered ingredients to make fireworks.  Somewhere in the background this had triggered an automated alert to the police, but a decimal point had been misplaced leaving them to think he had enough explosive to take out the whole village, rather than just launch a rocket into the air.  His wife is a helper at the youth club and is watching the plans for kids explosive night a little nervously.

Sodium hydroxide is *way* nastier than the H2 it'll produce so be careful if that's the generator you're thinking of.

jk

Most of the suggestions I was going to make have been made above, and most of the rest will probably get you onto some official watchlists.

However, for an impressive noise:effort ratio, the imploding drinks can trick?

gotta be careful with carbon based electrodes - oxygen plus carbon makes CO2, not always the O2 you desire. 

Whatever you do, don't accidentally create filings from the magnesium taper, realise your mistake, and set it aside outside the sight screen but close enough to catch a spark from the main experiment.

Tracers flying around the room is quite a powerful demonstration for the kids, but could land you in hot water.

I haven't caved in years but I think lighting has evolved away from carbide due to the arrival of led lighting rigs. It was pretty messy with the spent carbide often being dumped down the cave. I once (unintentionally) set fire to someone's hair trying to fix their helmet. He didn't realise until I started batting the side of his head!

Oxygen - hydrogen mixes need watching carefully.  I used to get 500ml drinks bottles sent down a corridor with a hydrogen /air mix. An underestimated hazard is the noise generated.  

My only hydrogen oxygen adventures were outside involving remote detonation and a drainpipe to direct the pop bottle projectile.  Using a sauce bottle as a student led to the bottle rupturing and a very loud bang - Moray House being next door to Parliament we feared the worst but you know, letting off loud bangs in Edinburgh at 13:00 arouses little suspicion.

This thread is definitely going on the 'Save' list

Yes, I hope you still have it when next we meet up. 

I did the Salter’s chemistry A-level when it first ran in the late 90s.  One day had an experiment going on with a reflux condenser followed by a nitration of toluene not under reflux.  Not good experiment planning…. Teacher watched us like a hawk…

yes good point, I should have emphasised the need for gloves, eye protection etc too, I presume hobby craft sell these when they sell the NaOH powder for soap making - so maybe buy them at same time (and don't add water to NaOH powder, mix in teaspoons of the NaOH powder into the full water container).

No worries, I had spotted the risk on this one.  If I do go ahead it will be adults only handling the NaOH and glass bottle.  The bit I need to decide is whether I'll let kids drop the aluminium in (while wearing appropriate PPE and probably holding long tongs).

One of the only bits of A-level chemistry I remember is that strong alkalis feel slippy if they get on your hands as they turn the fat in your skin to soap.

How about the oil barrel implosion demonstration... if you can source the oil barrel of course. Search YouTube if you need clarification 

Having read this thread, how are you lot still alive?

I’d love to see a custard explosion 

If one has access to oxy-acetylene gear ...

1 regular builders bucket, about half an inch of water, a thimble or two of washing up liquid well mixed in the water. Bubble it up with a 50-50 of O2/C2H2 mix, ignite using the longest stick you can manage.

LOUD! Was finding fragments of bucket weeks after.

Ear defenders recommended. 

I gave a warning about alkalis and soap on my first day with a Higher class.  End of the year they bought me a shed load of soap.  (I think it was because of my H&S spiel....)

Very good point about dissolving it.  Add the solid NaOH to water, never the other way around.  Just as you would when diluting conc. sulphuric.  

Not very safe 🤣 and balloon recommended instead as it has less plastic shrapnel 

To paraphrase jaws. "You're going to need a longer stick"

I don't think you'd like to see a big one! It's a serious hazard in custard factories. Several buildings have been destroyed with multiple casualties as a result of custard explosions.

Just found this with a quick Google:

In 1981, there was a dust explosion at the Bird’s Custard Factory in Banbury. A hopper – a container used to hold particles that have been collected from expelled air – became overfilled, creating a dust cloud of corn flour that ignited due to nearby electrical equipment. The explosion blew the roof off the building and 9 workers were injured. As custard is made when heat and water are added to custard powder, the water from the fire engines that came to put the fire out created gallons of custard inside the building, which then came pouring out.

I was the newly appointed deputy head of a First School in Bradford 35 years ago. It was my job to organise a firework display in the middle of the day...

I got the kids to stand well back in our inner city playground.  The bottle i put the rocket in fell over as soon as i lit it and spun first this way then that, pointing, first, at one group of children, then another, as they were lined up against the wall like condemned prisoners.

They survived.

Having mitigated that scenario, I rolled a giant PE platform out into the schoolyard and placed a Volcano on it. Lighting the blue touch paper, I then watched the whole PE table go up in flames. (It had a plastic sheet cover on top of its foam surface.) A plume of black acrid smoke rose into the autumn air. The children were rushed inside. I put the fire out with handfuls of wet modelling clay. 

Somehow I managed to have a career after that.

Do not have an "explosions night"!

It makes a very loud bang if you get a medium/large balloon, put on some safety specs and blow it up until it bursts.

Also, my physics teacher at school wired up a capacitor the wrong way with a few AA batteries and it went bang.

Had no idea custard was such a hazardous substance.  Wonder if it’s got a Dangerous Goods code - I’m going to have to look it up when I go into work next week.

Flour has been used in some pretty devastating mass murders in the past few years.  A flour mill on the Water of Leith (Dean Village) was destroyed by a flour explosion c. 1973 with several fatalities.  

Basically any fine dust/powder that's flammable (contains C & H) has the potential to be explosive when there's some oxygen about (air'll do) and an ignition source.

IIRC allowing flour to get a bit damp and then ferment in a relatively enclosed space is not the best idea.

Very hazardous, have a look at this sugar factory accident.

https://www.grupa-wolff.com/a-sugar-dust-explosion-in-an-enclosed-conveyor-...

Yeah, you don't want to be doing the original but if you scale it down to be a small crucible instead of a huge frying pan and use candle wax instead of vegetable oil and use a dropper to squish a little jet of water onto it, you can still see an impressive enough fireball while being safe enough in risk assessment terms. Not sure what you have to do the heating but something like a kitchen blowtorch could maybe be re-purposed for that...

I'm sure someone else already said this but make sure to try everything you plan to do multiple times to minimise the chances of a non-event as much as to do with safety, some of the things suggested are a little fernickety to get to work every time.

The OP _definitely_ doesn't want to using a boiling concentrated mixture of strong acids. If you don't want your face to melt off, this is a fume-cupboard only experiment!

I had a friend at school who made pipe bombs with fertiliser and something. I might still have his phone number if you’re interested.

Excuse me for being fernickety but don’t you mean pernickety?

Yeah, I had similar-  made gunpowder and put it in the hollow handle of a paint roller, it basically worked like a hand flare.  Gunpowder needs to be confined to explode.

Turns out I was looking for "finicky". Though I didn't know you could use pernickety to mean the same thing too.

Every day's a school day!

I did chemistry only to O level and we had years of avoiding "that soapy feeling as yor fat becomes soap"  - NaOH was wone of my main dislikes in the lab!

in my day setting fire to old TVs and seeing the old electrolytic capacitors fly into the air plus imploding Cathode ray tubes were the thing.  Marvellous how we survived really.

Report of the investigating officer

"Unable to investigate the scene as all of the evidence had been eaten by ruffians with spoons .."

Another one which can be loud and spectacular is messing around with capacitors.  Two options, one wire one up reverse polarity and watch the end explode, or alternatively get a large one fully charged up and then drop onto a metal sheet, the shorting of the legs causes a high voltage arc with a big flash and bang. Capacitor can either weld itself onto the metal sheet or take off like a rocket. Did both in first year of an electronics degree 20+ years ago as an example of why to be careful around capacitors!