Silver Halides - Periodic Table of Videos
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- čas přidán 11. 06. 2024
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Silver Nitrate into a solution containing halides. Also some talk about photography and cloud seeding. Discussed by Professor Sir Martyn Poliakoff. Dr Samantha Tang did the experiments for us.
Silver on Periodic Videos: • Silver - Periodic Tabl...
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To the people asking whether Silver Iodide is a pollutant:
Silver Iodide has been used to treat a variety of medical problems, but it's not something you'd want to consume for the fun of it as it's mildly corrosive. The people who managed it during the cloud seeding experiments also noticed some skin discoloration on their hands that lasted a few weeks but no weren't otherwise harmed.. The cloud seeding experiments resulted in atmospheric concentrations of, at most, a few nanograms (0.000000001 of a gram) per cubic meter... which is utterly minuscule. There are already relatively natural traces of Silver Iodide in the soil and no significant changes in that concentration were noticed. There was "estimated to be between 0.04 picograms/ml and 5 ng/ml" in the actual rainwater.
People who believe the government is intentionally poisoning the atmosphere with any number of things don't really understand, among other things, just how ineffective it would be to attempt to do such a thing by spraying chemicals from airplanes.
And besides, there are millions of cars on the road constantly emitting much more harmful things in much higher concentrations and I'm not just talking about CO2 and climate change.
I'm sure your related to Brian May from Queen.
I sort of remember this from school, but hearing it from you is far more epic
I love that they cut the scenes together right as he snaps lol
At 1:51
Its a very rare superpower that only elite chemists get
I had an awesome chemistry teacher in high school that set the state standards on fire with a bunsen burner on the first day. He based the bulk of his lab around qualitative analysis along with titrations and other classic experiments. As for the lecture portion of the class we took a ton of notes. In college I continued to use his notes and diagrams. Then, my first teaching job was high school chemistry so I got to pass on his notes to a new generation. Great memories. :-)
Another reason we'll never know what color a film emulsion is: all films contain dyes. A really long time ago, people made a film-like photo material on sheets of glass; these were "photo plates." Photo plates were really only sensitive to blue light. (Today this is called an Orthochromatic emulsion.) Early plates also suffered from a weird artifact: light would pass through the emulsion, reflect off the back surface of the plate's glass, and form halos around all the bright lights. The phenomenon is halation and lots of work went into solving it.
Finally a photo manufacturer was able to create a plate that didn't suffer from halation. Hermann Wilhelm Vogel, German photographer, bought a box and tried them. He really liked them...not only were they free of halation, they were sensitive to green light! Being a research scientist Herr Vogel wondered how they did it...so he took one of his wonder plates, soaked it in alcohol and discovered they had put yellow dye in the emulsion. He soaked the dye out of another plate under red light and made a photo on it...the green sensitivity was gone. This brought him to investigate the ability of dyes to sensitize emulsions...he found dyes that would sensitize silver halides to any color of light he wanted, and named these dyes Sensitizing Dyes. (Not all dyes will sensitize.) By using combinations of dyes he could make an emulsion sensitive to all colors, and these were named Panchromatic emulsions. No one truly understands the mechanism at play here - but they do know a dye that sensitizes to one particular band of light isn't necessarily one that has anything to do with that band - yellow dye stimulates for green light.
Is there a list of just sensitizer dyes, separate from other dyes?
A major use of AgI is in making sun glasses that automatically adjust themselves to the lighting conditions. AgI is added to the glass. Under low light, it's colorless. But when exposed to light, it dissociates into elemental Ag & I2, which are dark. The more intense the light, the greater the dissociation. I2 is volatile, but it can't escape into the atmosphere, since it's trapped in the glass.
In my chemistry class we had to figure out what halide was in 'mystery' chemicals A, B and C. While I was carrying out the test, my chemistry teacher came over to me and asked if I had the solution, to which I responded "No, sir. I have a precipitate of silver bromide."
3:30 woah. that'd be so awesome. please make it happen. i always wondered. i love analogue photography.
Agree. I would love to see a video about that.
A slow-mo video of photographic paper getting exposed to light
Take a piece of photo paper and place a solid object on it. Exposure it to light for 30 minutes then put it in the fixer. An outline of the object will visible. With enough exposure to light the emulsion is reduced to metallic silver.
Ron Garren
All development of film is slow. You don't need a chemistry professor to see that.
I mentioned this in a previous post... Photography is a really great topic within chemistry... Nitro-cellulose, AKA "gun cotton" was used as an early film media, that's why so many film warehouses burned... also why film during the 60's and 70's was called "safety film".
Baekeland, who invented Bakelite, was already wealthy from developing Velox photographic paper, made from natural polymers.
There's the whole photo-sensitivity topic, the exposure and development, as well as printing, 3 very different processes.... development and printing both have at least two different chemical agents, a developer and fixer...
I'd really like to know what goes on with the photosensitive materials... this includes not just silver-halide films, but also the yellowing and fading of photographic papers with age.
I know this isn't super exciting but I am currently doing my undergrad research on water chemistry and we are just starting to get a chloride method for studying the groundwater for important lakes in our area. We use the same method, but can quantify this with potassium chromate through titration. The product has extra hazardous waste, but the method goes from a lovely yellow to a brick red. I'm super excited to see a video on what I am actually doing since most of the experiments you all do I haven't had the luxury of being able to run them. Love your videos, they are very inspiring. Keep up the great work!
I think you'd be glad to know that many chemistry classes in High School (which is required) still do similar tests.
Even the basic chemistry course was still one of my most favorite classes, mostly because almost everything can be predicted (unlike English or history).
Although, in my school, we never actually did this experiment, but we still have to memorise how to do it and what colours it produces despite never seeing the silver halide test done. I wish that my teachers did choose to demonstrate experiments and tests like this, as seeing something happen in front of you makes it seem much more real and relevant than just blindly memorising facts out of a textbook. Hopefully finally seeing what the experiment looks like will help me to remember it in my upcoming exams.
Absolutely love this videos! Just started watching every single one of them:) The best part is the passion that emanates from people in this channel. As a scientist I think this is one of the most important things to be passionate about what you do and I totally love to see it in other people. Best wishes, Barbara.
Unexposed film is green!!! I work in a darkroom every day, :)
This was part of my "A" level chemistry exam back in 1964!
they taught this in HIGHSCHOOL?
man, I missed out on polio too, dang.
Insurance companies do hail suppression here. Storms that would generally produce golf-ball or baseball sized hail are seeded, and we get about half a foot of pea-sized hail instead. Same amount of precipitation, only with more condensation nuclei so there's a LOT of small hailstones rather than several gigantic stones. It looks like deep snow after those storms pass by.
Silver chloride photographic papers, as opposed to Bromide, were so slow that they were also known as gaslight papers. The inference was that they were so slow that they could be processed under gaslight. However, the term ‘gaslight’ also became associated with papers that were so fast that they could be exposed by gaslight. I believe that Kodak Velox paper (used for
contact printing, and discontinued in 1968) was a silver chloride type.
@putsome basilonit It's still being used, but not in the vast quantities of yesteryear.
I would absolutely love to see you do a darkroom chemistry video! ppppllleeeaaassseee??
Being a third year masters student in chemistry I love these videos and find them very informative and useful in the lab. Keep up the great work!
Would love to see an analogue photography chemistry video!
please do the darkroom video, I would love to see how silver is used as a catalyst for further crystal development! That would be awesome!!
In second semester of english classes during second year of university we had to prepare presentation, obviously connected to the course of our studies, ie chemistry, so I chose photography and devoted a large section to silver halide photography. Also, the lecturer used to play us some of your videos.
"Thailand Bureau of Royal Rainmaking".
And I thought MY country was excessively bureaucratic...
3,021! Getting the insanity out of the way..... Fascinating as always. Der professor is such a fantastic teacher. I do wish the tech was around to have him do teaching videos 40 years ago
I loved the clip, "Thailand Bureau of Royal Rainmaking and Agricultural Aviation"
Whoa whoa whoa... are you saying Martyn was *young* once?!
I used to work in a photolab so the silver halide processing is fairly familiar to me. Although, I worked with a digital photo lab not a film one; the process that the professor explains is kind of back to front with a digital lab. Instead of the silver bromide being on film, it's on the paper. The paper is exposed to the digital image with a laser at 600ppi and then the image is set with developer solution. The silver is present in the waste solution which is pumped out of the machine. The waste solution is then processed using an electrolysis reaction to make the silver attach to a metal cylinder (not sure what metal the cylinder was made of) and then collected by a technician. My tech used to show me the amount to silver that had been collected, the most I saw was over 2kg!
In the Australian alps they use cloud seeding in winter to accumulate larger quantities of snow that will flow into the hydro schemes and farm regions post winter. Obviously the snow enthusiasts were more than happy with the outcome.
That's so neat, I wish we had done that in my chemistry class.
I gotta say, Peropdic Videos has taught me so much, if i could I would travel to University of Nottingham just to learn from them directly :D
They didn't teach you how to spell. "Peropdic"
finallyyy!! i missed you guys :(
Precipitation reactions are my favoritr (particularly colorful ones)
When Prof. Brailsford over at Computerphile talks about the old bromide process for typesetters this is what he's talking about, good channel synergy (but a few years apart).
yes please explain the chemistry of photographic film technologies, from daguerréotype to the most recent color-negative and color-positive film.
Can you do a video on why the Olympic pool in Rio has turned green??
+InfiniteMushroom
I think he wanted to know the technical/chemical reason why it turned green."Lack of basic water sanitation" is pretty obvious here.
Latest info Sunday, August 14) says that a contractor added 80 liters of Hydrogen Peroxide to the pool. Why, I have no idea, never heard of peroxide in a pool. Anyway, they claim the Hydrogen Peroxide reacted with the Chlorine in the pool and 'deactivated' the Chlorine.
Sounds suspicious to me, as the sanitizing agent in Chlorine Pools is Hypochlorous Acid.
But it would be great to see this explained.
too much steroids in the water.
The water would be full of algae. Possibly from a warm climate or lack of putting chlorine in the water.
Maybe the professor might enjoy *Cody'sLab* channel? I'd love to see a collaboration video between the two channels some day. ^_^
Glad that you said digital picture and not digital photograph.
amazing tie !
Amazing Video
His Majesty the King of Thailand has a patent for inducing rain using this process. That is why the videos included in your video are from Thailand. They are rightly very proud of their King.
This video comes out and I'm here scanning my latest batch of black & white film. What a coincidence!
the video is just awesome!!👌👌👍
Awesome Video
Great science. Keep it up.
Oh please, Doctor! Do go in detail into the chemistry of photography please... a whole series on sensitive black and white and color films and the developing and fixing process... please.
professor, you're awesome
Certain people might watch this and think "Chemtrails confirmed!!!"
The like to dislike ratio is impeccable
For a second there I thought I read Silver Hairdos. ;) But seriously, this series is outstanding!
Minute physics did a video on how rain drops form. Water can't form big droplets by itself due to the fact that it takes energy to get it above a certain radius, but once it is at that radius energy is given out when it grows bigger. So for clouds to form they need soothing to get it started. In nature fungus spores released into the atmosphere which water molecules can then form around. In urban areas, dust and smoke released into the atmosphere are what the rain uses for a kick start instead of fungus. Silver iodide is just something else that works for these purposes, but they could probably just take some dirt up and release that into the atmosphere as a super fine powder and get the same result.
4:15 Chemtrails.
I guess the conspiracy nuts were actually on to something.
John Freeman well this is no secret, conspiracy nuts aren't exactly talking about making it rain in relation to the effects of chem trails.
Morru Qu'aan
I don't believe thats the purpose of Chem-trails.
Personally i think that its done to combat global warming.
Also because its not only a national but global security risk so they don't tell the civilian population because they can't risk any key countries going against the effort to combat global warming.
Health risks may also be in the calculation for not telling the civilian population.
They likely think the benefits of using cloud seeding to combating climate change outweighs the negatives of chem-trails affecting peoples health.
GRiMHOLD like i have said, this is not a secret and they don't do it very often.
This a science channel. How about you tackle your assumptions in a rigorous manner?
This video reminded me of Fresenius Qualitative Analysis we done did in high school (it was a chemistry focused high school). Yay memories... like that time I sprayed some sort of nickel participate all over the lab after doing a reaction.
Use a high speed camera to capture the color of the film when the light is turned on so you can see it change from the original color to the exposed color.
Oh i missed these videos... I hope new one coming faster than this one
5:42 can you use theobromine and silver iodide to make chocolate rain?
Make a video about touch powder!
Spectroscopy video!!! :) Yeah!Excellent!!! Greetings from Serbia and Montenegro!!! :D
Had this as part of my A level Chem practical 11 May 1966 Problem was that rather than giving us calcium chloride, they gave us calcium hypochlorite which was a pain. You didn't need to use silver nitrate, whatever you did you could smell the chlorine. BTW I passed even though I was more than a little drunk, it being the afternoon of my 18th Birthday.
Martyn you haven't changed a bit since highschool.
Yea, now we know what Jeremy Clarkson will look like at his age!
He won't change that much in 8 years.
Really?? Only 8 years between them?
I think you mean Sir Martyn.
What colour photographic film is? Those of us who are old enough (mind you, not really old), remember the film cassettes we used back then (or still use, we like film). These had a little piece of film (leader) protruding and the matte side was the emulsion side. Its colour wasn't the same between different films. I've seen beige films, magenta films, grayish etc...
This colour depends on the many things they're made of. For starters, all these film emulsions have gelatin as an ingredient. But silver halides aren't sensitive across the whole visible spectrum, they're only UV to blue sensitive. In order to make them sensitive to the other wavelengths of the visible spectrum, sensitising dyes are added, which certainly alter the colour of the photographic emulsion. Add to that any other antihalation and accutance dyes (these reduce light scattering within the emulsion and reflections off the film base) and you get quite a random colour.
Aww... When you said Sam was running the experiment. I thought we'd get to see her. It's been a while.
OMG YEESSS!!! CHEMISTRY OF FILM!!!!
Awesome
awesome 😍😍😍
Might have been helpful to some to run a replacement experiment using the likes of copper and Silver nitrate.
Utah has been doing cloud seeding tests since the 1970's during winter months to see if snow pack increases in select areas. Much of our water supply depends on mountain snowfall, so if it's possible to target specific areas for greater snow, it works out very well for our persistent drought conditions. Over the course of "19 winter seasons", target areas were shown to have
The problem with cloud seeding is you are stealing somebody else's rain. If a cloud passes over and doesn't rain on you it will rain somewhere else.
I think silver iodide being water soluble dissolves readily in the clouds because its a smaller molecule. Heat conduction of silver is so high that the water vapors builds so big that it accumulates mass without freezing because of the silver distributing the heat. Compared to water alone that freezes before it has enough mass to drop. 💧
great video! is silver iodide poisonous?
Has the prof ever done a video about nanoputians? I am curious to know if any of them are made of chemicals which have a practical use outside of their usefulness as teaching tools.
Oh man! It's all gone a bit cat in the hat in a box. Who knows if the cat is wearing the hat but I CAN STILL SEE IT GRINNING!
I trust him so much, I'd go into a darkroom with him and expect him to be perfectly cordial.
I wouldn't distrust a whole lot of people in that case, honestly. But this channel is indeed awesome :)
***** did you just assume their gender?
I tell you what though, in high school, we weren' allowed to be alone in the darkroom with the opposite gender.
Mostlyharmless1985
I tell you what xD
Fellow German?
Southern USian!
I still remember the smell of developer. I think it was some sort of quinone. A few photographers are said to have reacted with some sort of allergic reaction to that. Quinone is, if I remember it right, used by bombardier beeetles to great effect.
If you do some videos about the chemistry of photography, please remember to talk about colour photography, both dia-positives and negatives. I't really shows ingenuity.
And perhaps something about Polaroid photography. That has always been black magic to me.
AgNO3 + HCl -> AgCl + HNO3 I did the same identification as a student :)
Also, silver iodide I believe was the default for many years in photography; silver bromide is more closely associated with daguerreotypes on glass plates.
I wonder if you could get a visible light image of unexposed film by doing a combination of putting the film at liquid nitrogen temperature (might have to be actually in the vapor phase right over the liquid nitrogen) to slow the reaction rate and taking the picture with a strobe light and high-speed camera (so that any remaining exposure process doesn't have much time to occur)? To be sure you are really getting something approximating time 0, try increasingly short exposure times -- as you approach fidelity to time 0, you should get diminishing returns on shortening the exposure time.
hi would an electron microscope show the structure of undeveloped film and translate shapes/spacing into colour
Can you make a video about ultrium (celestrium)?
WOW iv got the same watch!
Haha, I remember doing these experiments in High School.
yayyy .. early for science!
I have an odd question for the professor or anyone who reads the comments. When I was 3 or 4 I had a dream where I was watching a presentation about mercury. What happened was there was a Tesla coil with mercury in it with a sphere of mercury on the op of it. When the Tesla coil was powered the sphere of mercury began to spin and glow but after a few minutes the sphere began to float. There were sparks going from the Tesla coil to the sphere of mercury. Do you have any explanation about this as in is this even possible? Or was it just a weird childhood dream. Thankyou
could you figure out the theoretical colour of unexposed silver bromide by simulating their electron clouds and calculating how photon absorption and emission would happen?
Chemistry of Film!
FINALLY! You haven't uploaded in a month. Or, um, you maybe were on vacation?
+periodic videos
Please do the photography videos. Both film & paper.
How quickly do solutions diffuse when the solute is still?
The color of unexposed silver halide is red. There are natural crystals silver bearing minerals that have a red color that fades to black on exposure to light. You only peek at your specimen rarely and quickly.
wait a minute... Department of Royal Rainmaking? How cool is that!
Talking about adding different chemicals into solutions, what exactly happens when you add poison into drinking water? Let's say you were drinking water from a pool, but on the other side someone spills a large amount of Arsenic or any other poisonous substance into the water- how long does it take for it to reach you?
1:51 This would make a pretty funky remix.
I wonder if a high speed camera and strobe light could show us the unexposed film faster than it can be exposed.
I had to do analytical chemistry just this past year.
in one sommer, our hail fighters didn't fly and then one of the most expensive hailstorms rained down on Stuttgart.
Is silver iodide toxic? What are the effects of it on humans or plants?
The silver iodide cloud-seeding process was invented by Bernard Vonnegut, whose brother Kurt was a rather excellent novelist.
it is good idea to end the drought in some places
Putting silver iodide in the air won't make water suddenly appear, the clouds need to already be there
You will explain Rio's green pool.
Could you talk about 25I-NBOMe, a chemical which is often sold in the streets as LSD, and the effects it might cause on the human body if consumed?
So if you have the silver iodide in rain couldn't you extract and refine it or would it be too small so you would need a whole swimming pool just to get 1 gram of it?
I would say even 1 gram out of a swimming pool full of rain water is overestimating it by sever orders of magnitude ;)
That's what I thought but I didn't want to go too big. I just wanted to make a point.
The quantity you would recover is the amount you put in. They showed one of the silver iodide flares they used. You know how much silver is in the flare and the area it rained in, that's how much you would recover. It would be more profitable to go to home depot (your dyi store profit.) And buy bags of sand and pan for gold. In the amount of sand to fill a sand box you can find a small amount of gold.
Why do they turn purpleish when exposed to light? Whats the chemistry?
Is silver Iodite toxic? I think this should have been said once spraying it in massive quantities has been brought up.