Anyone try the Mentos/Diet Pepsi experiments?

[crazyfrenchman27]

Quote:

Originally Posted by XxATOLxX I still like the idea of leaving a 2 liter bottle in the corner and filling it up with dry ice during a party.

The bottle would explode within a few minutes, depending upon the amount of dry ice.

-Matt

 

[jerb]

Dry ice is a bad idea (bottle will explode and it wont take several minutes, if you do it right it will take seconds, also it’s extremely sensitive to shock.)

As for the mentos aspect my friends and I have been doing it since at least last year. Only we've added our own little flair here and there.

We started off with coke and mint mentos and a paper launching tube. We then started experimenting. we've all done several papers on our results (easy A's) we used several different types of soda (Diet Pepsi, Pepsi, Diet coke, coke, cherry coke, vanilla coke, cherry Pepsi, mug, A&W root beer, ginger ale, store branded cola's, grape soda's orange soda's, etc) we've done separate experiments to see what the perfect number of mentos to drop in is (starting at 1 and going up to 30) we found that diet coke along with 11-14 mentos(one pack) is the best combination.

Other interesting things we've found is that diet soda's work better across the board compared with there regular sugared counterparts, this is because the sugar suspended in the solution restricts the CO2 from coming out of solution. Also diet sodas are pumped with more CO2 at the factory

Warm soda works better than cold or frozen soda though we cannot explain why this happens.

For anyone curious as to why this reaction takes place mentos contain a gelatinizing ingredient called Gum Arabic which reduces the surface tension of liquids. Also mentos have a chalky exterior which dissolves as they fall leaving millions of tiny pits on the falling mentos. These pits act as nucleation sites for CO2 bubbles to form on.

as for out modifications to this reaction: when we first started I wanted more height so I took a cylindrical aluminum blank and machined it into a nozzle that simply screwed on in place of the cap, we then took the mentos and drilled holes thin the center (most of them will split when you do this). The ones with holes in the center were then strung up to a piece of fishing line and suspended above the liquid surface. With the nozzle in place we'd drop these in and we'd get a serious fountain, usually around 20-25 feet.

Next we improved our launching mechanism, at first we were just using a rolled up piece of paper but we soon moved to a piece of vinyl tubing. Soon after that we went down to the science lab and grabbed some test tubes (these work the best). since we had to give the test tubes back we went looking for another source, we found them in a cigar shop, turns out some cigars come in glass tubes, we just asked the owner to save us a few and he did.

After a while you get bored of this, so we moved onto the next best thing, how do we make this reaction destructive? The answer was simple, get one person to hold the bottle, another to drop the mentos and as it started to explode have a third person standing by to screw on the cap to this exploding bottle. the reaction will pressurize the bottle so that cap can barely maintain the pressure (moving the bottle fast, dropping it, or squeezing it the smallest amount would result in the cap blowing off violently and soda spraying everywhere. we got this reaction down and we would throw the bottles, when they hit the ground the cap would blow and the pressure would propel them through the air like a rocket. you can also lay them on the ground and have some one run and kick it but we've had a few done that way backfire (2 liters bottle Vs. Crotch + pain)

Just a few things to consider if you’re going to try this

 

[Sovkiller]

Well indeed they did it with Coke not Pepsi...change the title to the thread!!!!!....

And has to be diet???

 

[JaGWiRE]

Quote:

Originally Posted by jerb Dry ice is a bad idea (bottle will explode and it wont take several minutes, if you do it right it will take seconds, also it’s extremely sensitive to shock.) As for the mentos aspect my friends and I have been doing it since at least last year. Only we've added our own little flair here and there. We started off with coke and mint mentos and a paper launching tube. We then started experimenting. we've all done several papers on our results (easy A's) we used several different types of soda (Diet Pepsi, Pepsi, Diet coke, coke, cherry coke, vanilla coke, cherry Pepsi, mug, A&W root beer, ginger ale, store branded cola's, grape soda's orange soda's, etc) we've done separate experiments to see what the perfect number of mentos to drop in is (starting at 1 and going up to 30) we found that diet coke along with 11-14 mentos(one pack) is the best combination. Other interesting things we've found is that diet soda's work better across the board compared with there regular sugared counterparts, this is because the sugar suspended in the solution restricts the CO2 from coming out of solution. Also diet sodas are pumped with more CO2 at the factory Warm soda works better than cold or frozen soda though we cannot explain why this happens. For anyone curious as to why this reaction takes place mentos contain a gelatinizing ingredient called Gum Arabic which reduces the surface tension of liquids. Also mentos have a chalky exterior which dissolves as they fall leaving millions of tiny pits on the falling mentos. These pits act as nucleation sites for CO2 bubbles to form on. as for out modifications to this reaction: when we first started I wanted more height so I took a cylindrical aluminum blank and machined it into a nozzle that simply screwed on in place of the cap, we then took the mentos and drilled holes thin the center (most of them will split when you do this). The ones with holes in the center were then strung up to a piece of fishing line and suspended above the liquid surface. With the nozzle in place we'd drop these in and we'd get a serious fountain, usually around 20-25 feet. Next we improved our launching mechanism, at first we were just using a rolled up piece of paper but we soon moved to a piece of vinyl tubing. Soon after that we went down to the science lab and grabbed some test tubes (these work the best). since we had to give the test tubes back we went looking for another source, we found them in a cigar shop, turns out some cigars come in glass tubes, we just asked the owner to save us a few and he did. After a while you get bored of this, so we moved onto the next best thing, how do we make this reaction destructive? The answer was simple, get one person to hold the bottle, another to drop the mentos and as it started to explode have a third person standing by to screw on the cap to this exploding bottle. the reaction will pressurize the bottle so that cap can barely maintain the pressure (moving the bottle fast, dropping it, or squeezing it the smallest amount would result in the cap blowing off violently and soda spraying everywhere. we got this reaction down and we would throw the bottles, when they hit the ground the cap would blow and the pressure would propel them through the air like a rocket. you can also lay them on the ground and have some one run and kick it but we've had a few done that way backfire (2 liters bottle Vs. Crotch + pain) Just a few things to consider if you’re going to try this

Interesting post. Why is diet coke the best, and have you guys tried any of your own liquids? It would be fun to see if you could create something even better then coke.

 

[jerb]

We haven’t tried anything of our own yet, not sure what we would make. If you made a liquid yourself it would have to be thin (so the gas could come out of solution with ease) but I would guess that you could pressurize different amounts of different gasses into a liquid to get the same effect. besides Soda works just fine and it’s readily available + cheap (also is it worth going through all this effort when you can make more volatile substances with ease? it seems like all the effort to make an test this new liquid would be better spent playing with fire and explosives

)

Another benefit is that it leaves you with a nice pressure tested bottle. Take some PVC (just big enough to fit inside the opening of the 2 liter bottle) with some O-rings and another PVC sleeve that fits over the tip of the bottle to lock in place. We use a larger section of PVC connected to the bottle with a ball valve. The whole thing looks like a large launcher, the idea behind it is to fill the two liter bottle with water (or another liquid) and put it on the barrel of this thing. then using an air compressor you fill the reservoir (no pressure is in the bottle at this point) you can then walk around with this thing, when you want to fire it you open the ball valve which allows the pressure to escape from the reservoir to the 2 liter bottle and when you pull the firing pin the now pressurized (80-100 PSI works nicely) 2 liter bottle goes flying! (The whole contraption looks very similar to a potato cannon except you carry it and its pneumatic)

I don’t suggest building the cannon referenced above unless you know what you’re doing. For instance you can only use sch 40 PVC DWV will shatter when pressurized (Plastic shards don’t show up on x-rays either!) if you want to try this route Google search Potato gun and design one

If you wanted to try something different you could try putting different chemicals into the soda, for example winter fresh lifesavers have gum Arabic, and a property of laundry detergent is that it reduces surface tension, also Gum Arabic can be bought cheaply in a pure form at theatre supply storms as "spirit Gum"

enjoy

 

[jerb]

lol that whole post and I didn’t even address your question:

"Why is diet coke the best?"

Across the board we found diet soda's performing better that their sugared counterparts. after lots of interviewing (I know a lot of engineers who got their degree's in micro fluidics and other related fields that helped me a lot). We have decided that the reason diet soda's work better is for some reason (I can’t remember it right now) diet soda's have more CO2 pumped into the mixture than the sugared counterparts. Also consider the amount of sugar in soft drinks, there’s tons! That sugar (though dissolved) is still a whole bunch of tiny particles suspended in the solution which stops the dissolved CO2 from forming bubbles and coming out of solution.

Is there a reason Diet coke works better than diet Pepsi or any of the other diet soda's we've tried? I have no idea, I would suspect it’s a difference in the recipe's that gives diet coke this attribute (I think it may also be the amount of CO2 pumped into them). For example go into your gas station when you fuel up next time and buy a diet Pepsi and a diet coke and drink them both, see if you notice that ones more carbonated than the other (I think Diet coke has more carbonation).

Also acidity might affect their reaction. Any chemists out there have some PH sensitive paper (for the life of me I can’t remember what there called). If you have these strips or any other means of measuring PH could you please measure both Diet coke and Diet Pepsi and then post your findings?

 

[The_Duke_Of_Eli]

From what I've read, it's some kind of chemical in the diet pepsi that reacts with it that's not in regular coke or not as much. The idea here is to increase the pressure. If you were to throw some mentos is (say 10) into a fug and put the cap on with a 1cm hole in the top of the cap, it would be much more impressive, or the cap would explode. I will be trying this June 23rd and oh yes, there will be videos.

 

[The_Duke_Of_Eli]

Quote:

Originally Posted by jerb Also acidity might affect their reaction. Any chemists out there have some PH sensitive paper (for the life of me I can’t remember what there called). If you have these strips or any other means of measuring PH could you please measure both Diet coke and Diet Pepsi and then post your findings?

You're thinking of litmus paper. The red/blue one. It's not very precise. I could probably get my hands on the school's PH probes and give you a very specific answer (within .1 ph) if you're really dying to know. I'd assume that the PH would be constant amongst all softdrinks, since the main chemical is CO2 gas. The sugar is significant but not too much so to PH. Maybe it'd change it a few tenths, but nothing astonishing.

 

[MdRex]

I tried this experiment with 5x mentos and 500ml Coke Light, the result wasn't as explosive as i would have liked (like 10+ft into the air) and my "volcano" made like 6-8 inch off the ground.

Anyone trying this with a beer?