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NEMO-Chemistry
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Science is magic

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 .
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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.
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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!

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blogfast25
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 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
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To moderate the force of the expansion you might want the molar ratio to differ from 1 to 1.

F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat with the evolution of chlorine.
NEMO-Chemistry
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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.
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@Nemo:

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

Thanks!

Morgan
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Mg burning instead of UV LEDs
Royal Society Of Chemistry
Fire and Flame 44 - Hydrogen and Chlorine Bang

Royal Society Of Chemistry
The Chemistry of Light 26 - Hydrogen & Chlorine Reaction

Some LEDs
Harvard Natural Sciences Lecture Demonstrations
Hydrogen and Chlorine Reaction

Further encased in a plastic sleeve
Hydrogen Chloride Cannon

Different LEDs
Photochemical reaction between chlorine and hydrogen

"Initiated by the radiation from a camera flash."
Hydrogen and chlorine gas

I kind of like this resonant effect of hydrogen burning in chlorine.
The sound of hydrogen burning in a large container of chlorine

Interesting mixing technique

[Edited on 25-8-2016 by Morgan]
blogfast25
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Thanks, Morgan!

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

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

100 % correct.

Too easy?

NEMO-Chemistry
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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 . 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
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 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.

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I confess i do like the look of LaTex! Something for the future though....
NEMO-Chemistry
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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 . Still alot to read but its well worth it.
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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  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
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 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.
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NEMO-Chemistry, I have since added some research on the H2/Cl2/Light chain reaction, that some may find interesting.
NEMO-Chemistry
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 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!
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