Sciencemadness Discussion Board

Science is magic

NEMO-Chemistry - 24-8-2016 at 03:01

I hate threads all over the place! But although related to couple of my others this is the one with the final display stuff in. I want to use it for some questions i have on other reactions i want to use.

The show and tell thing has been put back a week, its clashed with a whole school assembly so i get an extra week to perfect.

I am having problems with nitration but more about that much later.

I want to do a HCL and light experiment i have seen, basically its the mix Chlorine and Hydrogen in a quartz tube and use different coloured LEDS to show nothing happens until you get to Blue/UV wavelengths.

I have a way of doing it without quartz that involves the leds being inside the thick walled tube. The idea would be to put a clear screen around the tube and fire the stopper away from the audience and into the thick stage curtains. BUT while i think it would be a great display and really good for explaining light is energy, i am having doubts how safe it is.

I have seen the videos of it being done, the rubber bung seems to go with some force. I would use vacuum grease to try and make sure the stopper didnt get stuck, but how safely can this be done keeping the age range in mind?

I have some borosilicate very thick walled tubes, i can get a UV LED and other colours inside, or i could buy a small quartz test tube if needed. Anyone tried this out and any advice?

I am leaning towards not doing it, but it would be a missed opportunity if there is a safe way to do it.


I will get this out the way then post the final on the flash powder here, with pics. I will also post up the other demos i have settled for. The flash powder and the HCl are by far the most attention grabbing, with maybe one other that people seem to find really cool.

Amazing the stuff you could for a 'magic' show using chemistry and a bit of slight of hand :D.

Melgar - 24-8-2016 at 05:58

Thick-walled translucent polyethylene might not be a bad choice. Although you wouldn't be able to see much inside the tube, the walls would scatter the light from the LED, making it much more visible to the audience. You'd also have little to worry about in the way of a shattering tube.

mayko - 24-8-2016 at 06:07

I think you could go a step further and use such a demonstration to illustrate the quantum nature of light: no matter how *bright* a red light becomes, it will never initiate the reaction, whereas a relatively dim UV light might. It would probably be more eye-catching than watching the photoelectric effect on an oscilloscope trace!

blogfast25 - 24-8-2016 at 06:48

Quote: Originally posted by NEMO-Chemistry  

I want to do a HCL and light experiment i have seen, basically its the mix Chlorine and Hydrogen in a quartz tube and use different coloured LEDS to show nothing happens until you get to Blue/UV wavelengths.

I have a way of doing it without quartz that involves the leds being inside the thick walled tube. The idea would be to put a clear screen around the tube and fire the stopper away from the audience and into the thick stage curtains. BUT while i think it would be a great display and really good for explaining light is energy, i am having doubts how safe it is.



Are you aware of how the direct union between hydrogen and the halogens is moisture catalysed? Super dry mixtures of H2 and Cl2 are much harder to initiate (ignite, if you prefer) than those that contain traces of moisture.

Considering you're a relative beginner I would NOT contemplate anything that constitutes in essence triggering a small controlled explosion. There's also the question of UV dosage of course. Do you know how much W/m2 of specific UV radiation you need to reach initiation?

halogen - 24-8-2016 at 07:35

To moderate the force of the expansion you might want the molar ratio to differ from 1 to 1.

NEMO-Chemistry - 24-8-2016 at 09:30

Quote: Originally posted by blogfast25  
Quote: Originally posted by NEMO-Chemistry  

I want to do a HCL and light experiment i have seen, basically its the mix Chlorine and Hydrogen in a quartz tube and use different coloured LEDS to show nothing happens until you get to Blue/UV wavelengths.

I have a way of doing it without quartz that involves the leds being inside the thick walled tube. The idea would be to put a clear screen around the tube and fire the stopper away from the audience and into the thick stage curtains. BUT while i think it would be a great display and really good for explaining light is energy, i am having doubts how safe it is.



Are you aware of how the direct union between hydrogen and the halogens is moisture catalysed? Super dry mixtures of H2 and Cl2 are much harder to initiate (ignite, if you prefer) than those that contain traces of moisture.

Considering you're a relative beginner I would NOT contemplate anything that constitutes in essence triggering a small controlled explosion. There's also the question of UV dosage of course. Do you know how much W/m2 of specific UV radiation you need to reach initiation?



I know the UV Leds I have will do it, they are the same as the ones from the Royal society chemistry site where i got alot of the information from.

I used a teacher study pack, the damp gas i took to mean i could make both the Chlorine and Hydrogen and simply not dry the gases.

I have seen the reaction on several good sites the Royal society Chemistry site, this is what prompted my questions.

Its a fantastic demo especially using different coloured leds, my concern was using glass. I can make a safety shield etc but my unease made me ask here.

The UV dosnt bother me, the leds used can be brought as key rings and the level is low, its closer to black lights than it is to very shortwave UV i use for TLC.

Audience distance is 20 feet away so i dont see that as an issue.

Having said all that.........

My concerns were getting a prefilled tube out the box and putting in the set up ready to initiate, i was concerned that maybe stray sunlight would make it go off prematurely.

Dont get me wrong, i had pre decided if anyone said it wasnt a good idea or was a risk then i wouldnt do it.

Maybe i will put it on the burner for next year, its a shame but considering the age of the audience and what i am trying to do, i think if you have concerns then i will leave it for now.

I have something else i can replace it with, its not as spectacular by a long long way but my test audience likes it.

I had watched the periodic tables video of H2O2 and conc sulphuric acid having potassium permanganate poured into it, i liked the fact the red colour disappears straight away.

I had a whole idea how to get a an audience member to do something with me and have theirs go wrong because the solution wouldnt stay red.
instead i have something similar but using Phenolphthalein solution and citric acid dried in a tube etc.

I will do the UV experiment but not this year for them, it did make me nervous seeing the video's.

Thanks for the replies, i will post up the other experiments i am doing for them as soon as i have them perfected and photographed.

blogfast25 - 24-8-2016 at 15:40

@Nemo:

Can you link to the RSC H2/Cl2, UV initiated experiment?

Thanks!

Morgan - 24-8-2016 at 18:10

Mg burning instead of UV LEDs
Royal Society Of Chemistry
Fire and Flame 44 - Hydrogen and Chlorine Bang
https://www.youtube.com/watch?v=dBF3cfsPPOM

Royal Society Of Chemistry
The Chemistry of Light 26 - Hydrogen & Chlorine Reaction
https://www.youtube.com/watch?v=YNu2KeasN58

Some LEDs
Harvard Natural Sciences Lecture Demonstrations
Hydrogen and Chlorine Reaction
https://www.youtube.com/watch?v=NN82GoBG98s

Further encased in a plastic sleeve
Hydrogen Chloride Cannon
https://www.youtube.com/watch?v=BoC8LrNdnOc

Different LEDs
Photochemical reaction between chlorine and hydrogen
https://www.youtube.com/watch?v=Qox7WWZdOFM

"Initiated by the radiation from a camera flash."
Hydrogen and chlorine gas
https://www.youtube.com/watch?v=IYU7nQxdRG8&NR=1

I kind of like this resonant effect of hydrogen burning in chlorine.
The sound of hydrogen burning in a large container of chlorine
https://www.youtube.com/watch?v=nUzugUuwFVA

Interesting mixing technique
https://www.youtube.com/watch?v=xPVyAAkYwXk#t=1m45s

[Edited on 25-8-2016 by Morgan]

blogfast25 - 25-8-2016 at 05:51

Thanks, Morgan!

NEMO-Chemistry - 25-8-2016 at 12:05

Sorry i havnt had a chance to check which one it was. I am on the other PC trying to catch up on something i need to get done for school.

I am sitting a test Friday and Monday to see if i can swap over to chemistry, so watching videos on my nemesis (Balancing equations). If i can get that sorted for tomorrow and reasonably decent for Monday i am in with a chance.

Carbon and Oxygen to Carbon monoxide totally through me.Still not convinced i have it right but working on it :D.

NEMO-Chemistry - 26-8-2016 at 04:31

2C +O2 -----> 2CO Got there!! (I think). If this is right then its starting to click in place, anyone want to through some reasonable level (not too hard) ones up for me to practice?


Its taken shed loads of reading but i found a few videos that also helped, kind of like having a teacher doing an example for you to follow.




[Edited on 26-8-2016 by NEMO-Chemistry]

blogfast25 - 26-8-2016 at 05:33

Quote: Originally posted by NEMO-Chemistry  
2C +O2 -----> 2CO Got there!! (I think). If this is right then its starting to click in place, anyone want to through some reasonable level (not too hard) ones up for me to practice?


Its taken shed loads of reading but i found a few videos that also helped, kind of like having a teacher doing an example for you to follow.


Determine the coefficients of the reagents and reaction products:

Al + O2 = Al2O3

B + Cl2 = BCl3

As + S8 = As2S5

ScF3 + Mg = Sc + MgF2

Fe2O3 + H2 = FeO + H2O

If all the other coefficients are correct, what is x?

U + 2F2 = UFx

4 Fe + 3 O2 = 2 FexO3

Al + x F2 = AlF3


[Edited on 26-8-2016 by blogfast25]

NEMO-Chemistry - 26-8-2016 at 05:37

Thanks blogfast25, answer later once i get home. I appreciate the time taken to reply.

NEMO-Chemistry - 26-8-2016 at 06:58

Al + O2 = Al2O3
--------------------------
ANS
4 Al + 3 O2 = 2 Al2O3
--------------------------

B +Cl2 = BCl3

2 B +3 Cl2 = 2 BCl3
---------------------------
As + S8 = As2S5

16 As + 5 S8 = 8 As2S5

----------------------------
FcS3 + Mg = Sc + MgF2

2 ScF3 + 3 Mg = 2 Sc +3 MgF2

-----------------------------

Fe2O3 + H2 = FeO + H2O


2Fe2O3 + 2H2 = 4FeO +2H2O
-------------------------------------------------------------------

U + 2F2 = UF4

----------------------------

4Fe + 3O2 =2Fe2O3
----------------------------

2Al + 3F2 = 2AlF3

----------------------------------------------------

Sorry the formatting isnt consistent, the more i played with it the worse i made it! So I left as it is now.

Last one if i have it right was really utterly sneaky of you!! Almost threw me.

If i have the last one wrong then i blame.....erm will edit later when i think of who/what to blame :D.

Thanks for doing them, no idea how i did but kind of feels like a penny has dropped.

[Edited on 26-8-2016 by NEMO-Chemistry]

NEMO-Chemistry - 26-8-2016 at 07:05

I checked the videos, they are great, but none are the one i saw. I will try and find it, but Morgan basically found the same stuff by different people.

I didnt do the Roman numerals at the time because i hadnt got to that yet. I am doing transition metals and naming now, so i might come back and redo with the numerals.



[Edited on 27-8-2016 by NEMO-Chemistry]

NEMO-Chemistry - 27-8-2016 at 00:28

Ok put me out of my misery! How did i do?

I am having to work backwards a bit so i am up to speed with the others. Slowly grasping a few things, funny thing is the more you learn the more interesting it gets.

Is there any easy rules for polyatomics and charges? Or do you have to memorize them? Working on the naming thing with 'ous' 'ic' etc at the moment.

Might come back to that one and go back a step (course wise).

blogfast25 - 27-8-2016 at 04:07

Quote: Originally posted by NEMO-Chemistry  
Ok put me out of my misery! How did i do?



100 % correct.

Too easy?

NEMO-Chemistry - 27-8-2016 at 05:21

Quote: Originally posted by blogfast25  
Quote: Originally posted by NEMO-Chemistry  
Ok put me out of my misery! How did i do?



100 % correct.

Too easy?


I am a bit surprised, it took a while mainly because of the formatting! I did them on paper first which was much quicker. Difficulty wise i think you had it spot on, some took some head scratching but not to the point i wanted to give up.

I need to drop back slightly to do what was covered in the last week before the holiday, i hate having to work backwards like this but it shouldnt take long to catch up if i keep on top of the current work.

I do feel like i have finally grasped a concept! It is a good feeling :D. Chemistry feels like one hell of a learning curve (shear cliff face), but you cant beat the feeling of learning something you have struggled to get.

Thanks alot Blogfast25, i really appreciated the time and effort to do the questions. I didnt realise how long it can take to actually format it on here!

I will look at LaTex at some point and see how hard that is to grasp. I dont really want to put alot of effort into that until i am upto date with the actual chemistry side.

blogfast25 - 27-8-2016 at 06:03

Quote: Originally posted by NEMO-Chemistry  

I will look at LaTex at some point and see how hard that is to grasp. I dont really want to put alot of effort into that until i am upto date with the actual chemistry side.


LaTex isn't particularly helpful for reaction equations and cumbersome, compared to how we do it here. Just keep using suffixes and where needed symbols of state ('(aq), (s), (l), (g)').

But it's excellent for mathematics/physics equations. Even a generic reaction equilibrium equation like:

$$K=\frac{[C][D]}{[A][B]}$$

... looks great, compared to LaTexless renditions.

NEMO-Chemistry - 27-8-2016 at 07:15

I confess i do like the look of LaTex! Something for the future though....

NEMO-Chemistry - 27-8-2016 at 11:31

That pdf is really worth a read if anyone reads this in the future. Some of the advice on prep i might ignore, like the bit about filtering through Asbestos cloth!!

I will probably use bog standard filter paper :D. Still alot to read but its well worth it.

AJKOER - 28-8-2016 at 03:15


There are lectures out on the web outlining the basic steps of the Cl2/H2 explosive chain reaction mechanism, which is good educational material.

There is also a comment on how the presence of oxygen terminates the reaction chain [Edit] see, for example, https://books.google.com/books?id=0rx6Cjx_l-AC&lpg=PP1&a... and also http://www.jstor.org/stable/85775?seq=1#page_scan_tab_conten... with a similar intervention observed by O2 on the action of Cl2 with methane in light disrupting a chlorination reaction (see comments at https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/fun... ).

Note, H2 is very light and eager to escape, while Cl2 is heavy colored gas, with air somewhere in between these two, so an oxygen contamination may exist depending on how you are loading the gases. Theoretically, there may be a potential problem in the presence of water as:

Cl2 + H2O = HCl + HOCl

where the latter hypochlorous acid being unstable decomposing in the presence of light, organics, transition metal oxides (of iron, copper, cobalt,...), etc. Some decomposition paths (light, for example), proceeds as follows:

2 HOCl + hv = 2 HCl + O2 (g)

which may(?) introduce an oxygen termination step in the chain reaction. So think again if you are collecting your gases over water (which also contains dissolved O2), for example.

Bottom line, test your procedure before publicly performing it.

[Edited on 28-8-2016 by AJKOER]

[Edited on 28-8-2016 by AJKOER]

NEMO-Chemistry - 28-8-2016 at 03:27

Quote: Originally posted by AJKOER  

There are lectures out on the web outlining the basic steps of the Cl2/H2 explosive chain reaction mechanism, which is good educational material.

There is also a comment on how the presence of oxygen terminates the reaction chain. Note, H2 is very light and eager to escape, while Cl2 is heavy colored gas, with air somewhere in between these two, so an oxygen contamination may exist depending on how you are loading the gases. Theoretically, there may be a potential problem in the presence of water as:

Cl2 + H2O = HCl + HOCl

where the latter hypochlorous being unstable decomposing in the presence of light, organics, transition metal oxides (iron, copper, cobalt,...), etc. Some decomposition paths (light, for example), proceeds:

2 HOCl + hv = 2 HCl + O2 (g)

which may(?) introduce an oxygen termination step in the chain reaction.

Bottom line, test your procedure before publicly performing it.



Thanks for that.

At the moment i am not going to do it next week, i decided to leave it and maybe do it if i get invited back to do another 'show' at some point.

I will be trying this at home at some point, probably when i know a bit more and have a better safety screen or whatever.

If this goes well then i might do one based on gases, i really like the Chlorine with Hydrogen burning in it. The video i saw ignited it via a cannula of Hydrogen and one of acetylene to start it, this was in a large glass vessel of chlorine.

Doable but not yet.

I have mainly colour demo's for this show i am doing, so i might keep themed each time.

AJKOER - 28-8-2016 at 03:57

NEMO-Chemistry, I have since added some research on the H2/Cl2/Light chain reaction, that some may find interesting.

NEMO-Chemistry - 28-8-2016 at 04:35

Quote: Originally posted by AJKOER  
NEMO-Chemistry, I have since added some research on the H2/Cl2/Light chain reaction, that some may find interesting.


Thanks i will give it a read. I am hoping to try this out fairly soon, the reaction with light is a really good demo. Only reason i wont be doing it this time is simply safety.

I dont know enough and dont have enough time to make sure i can do this safely and make it work each time.

I will give the links a read..........once i get my homework finished :(. I got to do a book review, difficult as i only read text books!

woelen - 29-8-2016 at 06:42

A very impressive and fairly safe experiment is to use a flash light of a camera for initiating the explosion of a H2/Cl2 mix.

Practical setup:
In a thin glass sphere of 100...200 ml volume, bubble H2 such that it is appr. 50% full.
Next, bubble in Cl2 (do this in a dimly lit room), such that it is totally full. A few drops of water adhering to the glass are no problem.
Stopper the sphere tightly and put the sphere on a table, several meters away from the audience, behind a thick glass pane or perspex pane. The audience can see the glass bulb filled with H2/Cl2.
Take a big flash unit, connected to a photography slave unit. Put this flash unit behind the glass pane and direct it to the glass sphere with H2/Cl2. Adjust the flash unit, so that it gives a full blown flash when triggered.
Go to the audience and using a small camera with a real flash unit (not the LED thing of a smart phone) make a picture with flash enabled.
The small flash from the camera triggers the slave unit and this in turn triggers the big flash unit. At the instant of the very bright flash of the big flash unit, there will be a loud report of the explosion and the glass of the sphere will rattle against the glass pane.

This demo is VERY impressive and you should do it in a dimly lit room. Use candles or small orange/yellow LEDs for lighting to give it the right ambience and combine with suitable music. You can make a nice little show of this. Most impressive is that you can trigger the explosion from a distance and especially if you time the explosion with a climax in the music you can get a really nice effect. I once witnessed such a demo when I was much younger and it really sparked my interest.

IMPORTANT: First try your setup without the audience. It would be very shameful if nothing happens when the flash is triggered. Also important is to prepare the glass sphere with H2/Cl2 immediately before the experiment. Do not prepare the sphere in advance! Best is to have another person prepare the bulb while you tell your story. You can prepare the H2 and Cl2 in advance and bring them with you and just bubble these gases into the sphere under a concentrated table salt solution. Salt solution is better than plain water, because Cl2 dissolves quite well in water, but not so good in concentrated salt solution.

[Edited on 29-8-16 by woelen]

NEMO-Chemistry - 29-8-2016 at 08:44

Thanks Woelen, looks like its back on then! I better get some practice in over the next few days!

I appreciate the detailed description, I will have a go first on extremely small scale. I have a couple of those double ended Gas pipette type bulbs (not sure what they are called), they have a long cylinder type bulb with a tap each end.

I will use those for storing the gas and i have some glass syringes i can use to fill the reaction tubes.

Anyway i will have a play and see what works best. You are correct, i would be horrified if i let my little sister down in the show!

Morgan - 29-8-2016 at 09:08

I recall reading a vivid account of the first chemists discovering this UV initiation using black cloths over flasks and taking them outside to show the effect.
It brings to mind a building I was in at the university here where they had a lens and mirror tube device on the roof I guess that brought the image of the sun down and into a dim room whereupon it was projected on the wall, maybe 75 centimeters in diameter. It was really quite something to see the sun doing its thing live or 8 minute delay I should say. If there was or if there was some way to get enough UV in the image, imagine how succinct it would be to trigger a hydrogen/chlorine cannon effect as a quartz tube were placed in the roiling imagine of the sun with little solar flares and all.

NEMO-Chemistry - 1-9-2016 at 14:27

Show is tomorrow (Friday), i have had to drop some of the demo's for various reasons and cut the time to 20 mins.

BUT if it goes well then i get another crack at it for longer. I have everything prepared and have someone to assist (head teacher), i have practised and practised and although fairly basic, everyone i have tested it on has enjoyed it.

No script and its burned into my memory, i have watched so many videos to get an idea of delivery my head is spinning.

I will give details tomorrow of what i did and how it went, i will also start to prepare for the next one (hopefully).

Really looking forward to this and i have a definite theme, the idea is to show that magic can simply be a unknown (from the audience view point) concept in science.

So it starts out like a magic show (i have some really cool demo's and ways to deliver them), and gradually near the end i show them a couple of things but instead of saying water i tell them there is a chemical and what it is.

The idea is to show them that science isnt boring or out of reach of anyone prepared to study. For those with zero interest in science, i hope they simply enjoy what will appear as 'tricks' to them.

To others i hope it sparks the same interest in science i have.

Thanks to everyone for the help. I will post up what i did tomorrow (just in case of last minuet changes). The next one will be longer and more involved, i am hoping to include the demo's i have had to leave out this time.

I opted to cut a few out as i didnt have them perfected, i would rather not do them than do them and have it fail.

NEMO-Chemistry - 2-9-2016 at 03:01

Done and dusted, details later! Time to grab some lunch and go back to lessons :D.

NEMO-Chemistry - 2-9-2016 at 10:09

Ok it went really well, so well i wished i had someone film it. I did think about it but decided it would be a bad idea (especially if i messed it up).

I will post details of everything i did and what i will do for the next one. I left them with a question and everyone seemed really pleased.

I really enjoyed it. so next time (sometime next month) I get 45 mins which will be tough to do properly.

I made sure i didnt make the normal mistakes like saying Erm every other word (I hate demo video's where they say erm alot). It seemed smooth and coordinated but having not filmed it i cant look back and see what needs improving!!!

Oh well i will get it filmed next time.

I was ok nerves wise right up until the final 2 mins before it was time to start!!!! I froze behind the curtain solid, but fortunately i had an entrance planed and as soon as it went off i just went on with the show.

So lesson learned, it definitely pays to practice and practice. thats way even if you freeze just before you start, you go into auto mode as soon as your start up fires.

Anyway if anyone wants a break down i will do it later, for the next one i need to perfect nitrations, i used it once for the start but didnt go through with the coloured version this time. My nitrations were not consistent enough but the start one went ok.