A Safer "Rainbow Flame" Demo for the Classroom
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- เผยแพร่เมื่อ 7 ก.ค. 2024
- Demo instructions available here:
www.acs.org/content/dam/acsorg...
(note: this demonstration does not require barium chloride, which is toxic -- the video demonstration does not include this compound)
A C&EN infographic on the demo is available here: cenm.ag/labdemo
A chemistry demonstration commonly known as the “rainbow flame” experiment has resulted in a number of serious injuries in classrooms in recent years. The experiment is meant to show how various metal salt solutions can create flames of different colors, but it can be unsafe if teachers use highly flammable solvents like methanol or ethanol in the procedure. To prevent future injuries, the American Chemical Society (ACS) Committee on Safety recommends that rainbow flame experiments involving flammable solvents be discontinued immediately. In this new video, Kim Duncan and James Kessler of the ACS Education Division demonstrate a much safer alternative using the same metal salts dissolved in water (rather than in ethanol or methanol).
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check in if you here due to online classes cause of the rona
Hello-
TheOfficial KV yup
*indeed*
Yessir.
aloha
who's here and currently confused why this is hw
We do this with Q-tip swabs soaked in the metal salts in water solutions. The Q-tip won't catch fire until well after all the metal salt has burned off and the students can see the color very well. They then put the used Q-tip in a beaker of water that is disposed of. Easy, safe and effective. Students love it.
Do you throw the q-tips in the trash once finished? or do you dispose of them as chemical waste?
Calcium deep orange
Copper blue green
Lithium deep red
Calcium pinkinsh
Sodium yellowish orange
Scrontium orange red
a king
the last calcium is actually potassium :)
a king indeed
so many chem students owe you
omgg no joke a king. I have an essay due and you have no idea how much your comment saved me time
when you see the flame of pottassium through a cobalt glass you can see that purple colour well.
I'm not surprised that safety is at the forefront here, given the most recent (completely avoidable) incident involving the methanol-solutions version of this demo. I do agree this is a far safer method for flame tests. But aren't we crossing over into paranoia to recommend an *impact shield* for holding some soaking wet wood splints into a burner? I'm all about keeping kids (and teachers!) safe, but this just seems way over the top. Maybe everyone in the room should wear respirators or haz-mat suits while are at it? ;) These kinds of blanket statements (whether they are from the National Fire Protection or re-stated by the ACS) do have a cost associated with them: unnecessary bans and impediments to great science teaching.
The precautions are stupid when you think about grilling steaks
I remember this experiment very clearly from high school chemistry class being performed by my teacher and a lab assistant in front of each of my classes lab groups one group as a time and thought it was one of the “cooler” experiments because we could see the “Rainbow” of metal salts burning all at one time in beakers. For the life of me if this experiment is done properly (borosilicate glass beakers, less than 10ml of Ethanol (not Methanol), beakers extinguished and allowed to cool fully before adding additional metal salts or Ethanol, Never pouring Ethanol from bottle into beaker, lighting the beakers with a split from a meter or more away, and keeping students a meter or more away while the experiment is burning, and a lab assistant manning a fire extinguisher while the experiment is being demonstrated.) that this experiment can go wrong. My guess the reason that this experiment has gone wrong recently is the teacher added more solvent Methanol or Ethanol to beakers that are burning or still hot, in other words not following common sense lab safety protocol.
Thank you for sharing your comment. The American Chemical Society (ACS) and the American Association of Chemistry Teachers (AACT) recommends that the traditional “rainbow demonstration,” which may be performed on an open bench using flammable solvents such as methanol, be discontinued immediately. For more information about this recommendation, please see the following resources:
ACS and AACT endorse the “Safer Rainbow Flame Demo” Detailed instructions for high school chemistry teachers can be found here: teachchemistry.org/classroom-resources/flame-test-rainbow-demo
For more information on the dangers of the old-school rainbow flame demo, please watch this video produced by the Chemical Safety & Hazard Investigation Board. It features Calais Weber, a high school burn victim who was injured during a rainbow demonstration in 2006:
th-cam.com/video/g6vR0BdRCNY/w-d-xo.html
This month (July 2019), a settlement was reached regarding NYC high school students who were also horrifically burned during a Rainbow Experiment in 2014:
www.nytimes.com/2019/07/01/nyregion/alonzo-yanes-burned-school-chemistry.html
www.cnn.com/2019/07/02/us/new-york-chemistry-experiment-injuries-damages-trnd/index.html
ACS Safety Alert: cen.acs.org/articles/92/i11/Safety-Alert-Rainbow-Demonstration.html
Great job!
Lithium, Li+ Red
Sodium, Na+ Yellow
Potassium, K+ Lilac
Calcium, Ca2+ Orange-red
Barium, Ba2+ Green
Copper, Cu2+ Blue-green
Strontium (Sr+) Red
Thank you so much for this video. I'm a writer and am current writing a children's story based on the old Are You Afraid of the Dark series from the 90s and I wanted to come up with a cool but safe way for the kids in the story to make their campfire burn like a rainbow when they add their "Midnight Dust" to it for effect.
What’s your book called
What works even better is to make an AQUEOUS soln of the salt. Get a asthma nebulizer and put the solution in the nebulizer cup. Turn on the nebulizer and aim the mist into a bunsen burner. Works great. Takes a minute for the flame to get its color.
This is the safest way to conduct a flame test experiment.
can I discard the wooden splints in the trash once completed or do I need to dispose of them as chemical waste?
What is the name of the bunsen burner that you are using? I would like to purchase the same model.
please help me i need help with kcl
how come the Bunsen burner is giving a flame that has no color?
The combustion is complete, or almost complete, so there is none of the oily, sooty flame that is caused by not enough oxygen in the mixture.
Just curious... what evidence is there that the colors observed in the flame tests are due to the metals, and not the nonmetals in the compounds tested?
The other compound in all the salts is the same - chloride.
she forgot gloves lmfaooo
she looks like that teacher that never lets you go to the bathroom
dead
Suppose to use platinum wire
If it's rainbow then where is the black
Black aint in the rainbow
I will remember that "NaCi" called sodium chloride. I thought it called natrium chloride 😅. bless your science school
Which languages do you speak?
Sodium chloride is NaCl
And your so blessed that you were not born in srilanka 🤣
La PUCP me trajo aquí :V
x2
can someone write a paragraph explaining why the flames are different colors for me? thanks😜
look who just got ignored lol
those salts are made with metals of the 1st and 2nd group of the periodic table and it has something to do with the electrons in the last shell of the atoms but don't take my word for that cuz i'm not sure
Because you “ad energy” by heating the metal atoms up. That causes the/an electron in the outer orbit to “jump” outwards to an orbit further out from the nucleus. When the energy is “spent” the electron falls back to it’s original position, releasing a foton (a light particle), Depending on which metal that foton has a different wavelength seen by us as different colours.
oj KEMIJA 8
3:16
ma'm almost set the whole place on fire
Using saturated solutions like this is wasteful and not needed. The old method using spray bottles and 0.1m (aq) solutions is far more effective. Use distilled water for the students and have an ethanol set for a demonstration by an experienced teacher or technician.
i reported