Chemistry Safety

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Levi
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Chemistry Safety

Postby Levi » Tue Nov 02, 2010 1:29 am UTC

I'm teaching a science class for middle schoolers. It's a once a week thing on Fridays and is really more about giving the kids something fun to do once a week than to actually teach science, so we mostly do science-related things like rockets, basic electronics, etc. I'm planning on doing some semi-dangerous things in the future, and I'm hoping some of you know how to make it unlikely that I will accidentally manslaughter my students.

Next class I'm going to have them experiment with dry ice. I'm going to pass out goggles (they're in middle school and there's a possibility of them dropping it/throwing it at each other/doing some other stupid thing) and gardening gloves. That should be enough, right? I'm also planning on doing it outside, because I'm not sure how good the ventilation in the room we're going to be in is, but I'd like to do it inside if it's safe because it's pretty hot out. It's in a room that's maybe... thirty feet to a side? I'm really bad at estimating. It's part of a much larger room, but it's separated by dividers. I've not noticed any air conditioning vents, but I didn't think to look for them. So, is it alright to do it in there? There are around ten or fifteen kids in the class and I'm going to be giving each of them a block of it. Also, are there any other precautions I should take?

Later on I'm planning to teach some chemistry stuff and do this. I looked up the chemicals on Wikipedia but it wasn't very enlightening. According to the comments on the blog the sodium thiocyanate is poisonous. I won't be giving any to the kids. Do I need to do anything special other than wash my hands afterwords and not snort it?

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Clever-Username
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Re: Chemistry Safety

Postby Clever-Username » Tue Nov 02, 2010 2:46 am UTC

Sodium Thiocyanate has a pretty vicious MSDS sheet: (This is for a 98-100% concentration of the stuff, check what % your mixture is, the less it is the less harmful it will be)

http://www.jtbaker.com/msds/englishhtml/s5210.htm
Inhalation:
May cause irritation to the respiratory tract. Symptoms may include coughing and shortness of breath.
Ingestion:
May cause vomiting, disorientation, weakness, low blood pressure, convulsions and death which may be delayed. The probable lethal dose is between 15-30 grams.
Skin Contact:
Causes irritation to skin. Symptoms include redness, itching, and pain.
Eye Contact:
Causes irritation, redness, and pain.
Chronic Exposure:
Prolonged or repeated skin exposure may cause dermatitis. Repeated ingestion of small amounts may cause hives, abnormal bleeding, enlarged thyroid, weakness, confusion, diarrhea, psychosis, and collapse.
Aggravation of Pre-existing Conditions:
No information found.

If you plan on putting this on your skin don't leave it there for too long.

Another thing you might want to do is some Sodium or Potassium in water (outside behind a protective shield of some sort if you're using potasium).

Edit - For the dry ice, close supervision is definitely a must, you might want to get another adult/teacher around to help with watching the kids. You definitely don't want them trying to eat it, but as long as they wear their goggles and protective gloves you should be fine. One thing you might want to do to show them something cool is put some dry ice in a beaker and take a plastic shot glass and plug the opening of the beaker with it... wait... the thing will pop off and rocket up to 20 feet in the air. Always a cool demo.

If you can get your hands on some liquid nitrogen you can show them how dangerous it is by putting objects in it and smashing them on the wall/ground afterwards. You can then show that it's just nitrogen gas and not something lethal by pouring some water in your bucket of liquid nitrogen and blowing the resulting *steam* towards them; completely harmless, but so cool, gotta make sure they dont touch the liquid though of course.

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Levi
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Re: Chemistry Safety

Postby Levi » Tue Nov 02, 2010 3:25 am UTC

Spoiler:
Clever-Username wrote:Sodium Thiocyanate has a pretty vicious MSDS sheet: (This is for a 98-100% concentration of the stuff, check what % your mixture is, the less it is the less harmful it will be)

http://www.jtbaker.com/msds/englishhtml/s5210.htm
Inhalation:
May cause irritation to the respiratory tract. Symptoms may include coughing and shortness of breath.
Ingestion:
May cause vomiting, disorientation, weakness, low blood pressure, convulsions and death which may be delayed. The probable lethal dose is between 15-30 grams.
Skin Contact:
Causes irritation to skin. Symptoms include redness, itching, and pain.
Eye Contact:
Causes irritation, redness, and pain.
Chronic Exposure:
Prolonged or repeated skin exposure may cause dermatitis. Repeated ingestion of small amounts may cause hives, abnormal bleeding, enlarged thyroid, weakness, confusion, diarrhea, psychosis, and collapse.
Aggravation of Pre-existing Conditions:
No information found.

If you plan on putting this on your skin don't leave it there for too long.


Guess I won't be doing that, then. Any suggestions on another way to do it or maybe some sort of similar reaction with a dramatic change?

Clever-Username wrote:Edit - For the dry ice, close supervision is definitely a must, you might want to get another adult/teacher around to help with watching the kids. You definitely don't want them trying to eat it, but as long as they wear their goggles and protective gloves you should be fine.


I'm technically the assistant. The teacher of the class asked if I wanted to help out and she said I could run the whole show if I wanted, so I jumped at the chance. I have some help.

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Minerva
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Re: Chemistry Safety

Postby Minerva » Tue Nov 02, 2010 4:49 am UTC

Clever-Username wrote:Sodium Thiocyanate has a pretty vicious MSDS sheet: (This is for a 98-100% concentration of the stuff, check what % your mixture is, the less it is the less harmful it will be)


Every MSDS for every chemical sounds scary.

Look at this MSDS for water - it is a good example of how most of the content in MSDS sheets is just scary sounding crap that is written in there by default for every compound.

http://www.piercenet.com/msds/EN6797.pdf

Anyway... sodium thiocyanate. It's pretty harmless. Don't eat it, don't put it in your eyes, nose, open wounds etc. I'm sure if the person demonstrating this on that webpage you linked had died a grisly death, it wouldn't have been posted.
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Re: Chemistry Safety

Postby Sir_Elderberry » Tue Nov 02, 2010 4:56 am UTC


Eye contact
: Immediately flush eyes with plenty of water for at least 15 minutes, occasionally lifting
the upper and lower eyelids.

"He drowned...in recursion."
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big boss
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Re: Chemistry Safety

Postby big boss » Tue Nov 02, 2010 6:26 am UTC

Sir_Elderberry wrote:

Eye contact
: Immediately flush eyes with plenty of water for at least 15 minutes, occasionally lifting
the upper and lower eyelids.

"He drowned...in recursion."


Are those first aid measures jokes? Seriously that seems...
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Re: Chemistry Safety

Postby HungryHobo » Tue Nov 02, 2010 11:30 am UTC

gotta make sure they dont touch the liquid though of course.


When I was a kid they had an open day at the university.
LN is one of those weird substances which is both dangerous but also surprisingly hard to injure yourself with.

They did all the tricks,poured some out on the ground and me and the other kids spent a while running around stamping on blobs of nitrogen.
We even got to stick our own flowers in it and break them under supervision.
Hammering a nail in with a banana is all good.

As long as you don't stick your hand right into the beaker of it or drink it you're safe enough.

there's some nice demonstrations that end with a small quantity being thrown at the audience who all cringe away only to be hit by nothing but white smoke.
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Re: Chemistry Safety

Postby justaman » Tue Nov 02, 2010 7:50 pm UTC

How about hydrogen soap-bubble towers? You can light them which will produce a large sheet of flame.

H2 bottle rockets, mix H2 and O2 in a small bottle with a tiny vent in the lid for lighting, aim away from students and light the vent, the bottle should fly across the room as the lid pops off.

The Briggs-Rauscher Oscillating Color Change Reaction is pretty cool, though rather slow.

Thermite is cool, as is touch powder.

There seems to be some good stuff on that last site, lots of very simple demos which would be good for those younger students.
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big boss
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Re: Chemistry Safety

Postby big boss » Tue Nov 02, 2010 8:26 pm UTC

justaman wrote:.

Thermite is cool, as is touch powder.



You can even put thermite underwater and it'll burn if I remember correctly, I think grade school kids would enjoy that. The only protection you need is one of those blast screens and a face mask/thick lab coat.

edit: There is this one professor at my university who always has these big chemistry demos and the auditorium is filled with college students, Ill see if I can remember any of the demos later.
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Re: Chemistry Safety

Postby Clever-Username » Thu Nov 04, 2010 3:21 am UTC

HungryHobo wrote:
gotta make sure they dont touch the liquid though of course.


When I was a kid they had an open day at the university.
LN is one of those weird substances which is both dangerous but also surprisingly hard to injure yourself with.

They did all the tricks,poured some out on the ground and me and the other kids spent a while running around stamping on blobs of nitrogen.
We even got to stick our own flowers in it and break them under supervision.
Hammering a nail in with a banana is all good.

As long as you don't stick your hand right into the beaker of it or drink it you're safe enough.

there's some nice demonstrations that end with a small quantity being thrown at the audience who all cringe away only to be hit by nothing but white smoke.


Yea I put on a demonstration for the public as part of national chemistry day with my university. It maybe difficult to hurt yourself if you're being smart, but picking something up the wrong way after it's been in the liquid or mishandling something and you'll get a NASTY burn. With kids in this age-range it's imperative that a no-touch policy is set up.

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Re: Chemistry Safety

Postby masher » Thu Nov 04, 2010 3:34 am UTC

big boss wrote:
Sir_Elderberry wrote:

Eye contact
: Immediately flush eyes with plenty of water for at least 15 minutes, occasionally lifting
the upper and lower eyelids.

"He drowned...in recursion."


Are those first aid measures jokes? Seriously that seems...



and in the event of a small spill, dilute it with water and mop it up...

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Re: Chemistry Safety

Postby MarvinM » Thu Nov 04, 2010 8:59 pm UTC

big boss wrote:
You can even put thermite underwater and it'll burn if I remember correctly, I think grade school kids would enjoy that.


I'm not sure you do, the damp mixture will not ignite and molten iron falling into water can explode, launching glowing iron some distance.

My only close experience with thermite is when a teacher tried and failed to make it work. He used magnesium ribbon as a fuse. Summery of what I've read suggest the aluminium powder should be newly opened, the ferric or ferrous oxide should be very dry (try baking it first) or the reaction spatters and a sparkler is supposed to work well as a fuse/igniter. Flower pots can explode on contact with the molten iron. This isn't the sort of thing to be trying first time in front of an audience.

As for dry ice, when I was 17 I attended "fun and games with liquid air" in which dry ice pellets were thrown into the audience, so long as you keep a pellet moving in your hand, it's perfectly fine. The wrong gloves can make things much worse as if the cold penetrates they are very hard to get off quickly. No gloves can often be better than with. LN2 is similar, you can splash people with it using bare hands if you are quick, but spill on clothes and the burns can be severe.

For safe ideas I recommend "Chemical demonstrations" by B.Z. Shakhashiri, a university library should have a set and well worth tracking down.

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Re: Chemistry Safety

Postby HungryHobo » Thu Nov 04, 2010 11:08 pm UTC

MarvinM wrote:As for dry ice, when I was 17 I attended "fun and games with liquid air" in which dry ice pellets were thrown into the audience, so long as you keep a pellet moving in your hand, it's perfectly fine. The wrong gloves can make things much worse as if the cold penetrates they are very hard to get off quickly. No gloves can often be better than with. LN2 is similar, you can splash people with it using bare hands if you are quick, but spill on clothes and the burns can be severe.

there's apparently some old party piece where you can put a little LN in your mouth and shoot smoke from your mouth and nose.
Some foolish student actually *drank* LN and ended up losing a lung and chunks of his stomach.
details: in the mouth it hovers on a cloud of it's own steam, in the throat or stomach it can't do the same due to pressure and constricting muscles+turbulence and long story short makes for a very bad day for the foolish person.

Liquid oxygen is cool cause it responds to magnets.
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Re: Chemistry Safety

Postby Sir_Elderberry » Thu Nov 04, 2010 11:15 pm UTC

A professor at my university has a trick where he puts LN into his mouth and immediately spits it back out, which looks really cool. Apparently last time he went to the dentist the dentist was absolutely baffled at all the tiny cracks in his teeth...
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Re: Chemistry Safety

Postby Dopefish » Thu Nov 04, 2010 11:25 pm UTC

At the other temperature extreme of cool demos, apparently it's possible to dip a wetted finger quickly into molten metal and the steam layer that is formed keeps you from being burnt.

Of course, molten metal is probably a bit more impractical than LN2, but I figured it was worth mention.

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Re: Chemistry Safety

Postby MarvinM » Fri Nov 05, 2010 12:17 am UTC

Obligatory wikipedia link underlying several previously explained demos.

http://en.wikipedia.org/wiki/Leidenfrost_effect

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Re: Chemistry Safety

Postby Minerva » Fri Nov 05, 2010 8:02 am UTC

justaman wrote:H2 bottle rockets, mix H2 and O2 in a small bottle with a tiny vent in the lid for lighting, aim away from students and light the vent, the bottle should fly across the room as the lid pops off.


You could probably do that more safely with a mixture of hydrogen and a bit of air... I think a hydrogen-oxygen mixture would violently explode.
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Re: Chemistry Safety

Postby arbitrary value » Sat Nov 06, 2010 9:33 am UTC

I'd be careful with anything very cold; when I was an undergrad, a grad student dropped an empty, sealed test tube into liquid nitrogen. It imploded and a shard of glass flew right into her eye. She was eventually fine (more or less) but we all had to wear goggles around liquid nitrogen after that.

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Re: Chemistry Safety

Postby justaman » Sat Nov 06, 2010 9:09 pm UTC

arbitrary value wrote:I'd be careful with anything very cold; when I was an undergrad, a grad student dropped an empty, sealed test tube into liquid nitrogen. It imploded and a shard of glass flew right into her eye. She was eventually fine (more or less) but we all had to wear goggles around liquid nitrogen after that.

Good practice for working with any dangerous liquid (acids, bases, oxidisers, etc.) dictates always wearing a face-mask or goggles while working with it. As the OP is in a school, I would imagine this is mandatory anyway in the chem labs.
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Re: Chemistry Safety

Postby Levi » Sat Nov 06, 2010 11:32 pm UTC

Actually, we don't have chem labs. This school is terrible at science education; we rent space from a church and the science textbook is written by a creationist. We do have plenty of goggles, though. I did the stuff with dry ice yesterday and the kids loved it and no one was hurt. Next week I'll be doing heat and fire. I'm going to do mostly demonstrations for that. After that I'll do the stigmata thing and the chemistry, but it will be a few weeks since the class won't meet for a while after this Friday.

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Re: Chemistry Safety

Postby HungryHobo » Sun Nov 07, 2010 8:14 pm UTC

Levi wrote:After that I'll do the stigmata thing and the chemistry, but it will be a few weeks since the class won't meet for a while after this Friday.


stigmata???
please tell me that was a typo.
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Re: Chemistry Safety

Postby Sartorius » Sun Nov 07, 2010 10:14 pm UTC

Sir_Elderberry wrote:

Eye contact
: Immediately flush eyes with plenty of water for at least 15 minutes, occasionally lifting
the upper and lower eyelids.

"He drowned...in recursion."


The MSDS is for distilled/pure water, which is actually quite painful if you get it in your eye, because the amount of solutes in your cells causes the water to enter them and could potentially lyse them.

The more you know...>_>
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Levi
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Re: Chemistry Safety

Postby Levi » Sun Nov 07, 2010 10:30 pm UTC

HungryHobo wrote:
Levi wrote:After that I'll do the stigmata thing and the chemistry, but it will be a few weeks since the class won't meet for a while after this Friday.


stigmata???
please tell me that was a typo.

Levi wrote:Later on I'm planning to teach some chemistry stuff and do this.

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Re: Chemistry Safety

Postby drraspberry » Sat Nov 13, 2010 6:54 pm UTC

Screaming jellybaby is a good one for school kids, although more as a demo than a experiment for them. Potassium Perchlorate and a Jelly Baby. Heat it and all the sugar gets oxidised at once and the jelly baby burns while making a screaming noise:P However, if you want something they can do, Borax/glue slime is great 8)

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Re: Chemistry Safety

Postby whereswalden90 » Wed Nov 17, 2010 7:51 pm UTC

I feel this is necessary in any discussion of chemistry safety:
http://www.flickr.com/photos/blacklovei ... 2556853/#/
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