Make Silver Testing Solution to Detect Fake Silver

Make Silver Testing Solution to Detect Fake Silver


Warning: Nitric acid is corrosive, while dichromates and chromates are carcinogenic. Wear gloves when handling them. Greetings fellow nerds. In this video we’re going to make a silver testing solution to determine the authenticity of silver metal. This is the same solution sold commercially and online. We’re going to reproduce it here as well as explore the chemistry. First we start 0.5g of a dichromate or chromate salt. You can use just about any salt including potassium dichromate, ammonium dichromate, or sodium chromates. They’ll all work. To this we add 10 mL of deionized or distilled water. Now give it a shake. To this solution we add 7 mL of concentrated 70% nitric acid. Now cap it up and shake it until all the chemicals dissolve. We want a solution of dichromate ions but we can use chromates because under the highly acidic conditions the chromate ions convert into dichromate ions. And there is our test solution. So let’s give it a try. This here is an authentic piece of silver. At least I’m pretty sure it is. To test it all we do is apply a drop of the testing solution to the surface. The reaction takes a minute or two so you have to be patient. If this is authentic silver then what happens is the nitric acid in the solution dissolves a small amount of silver to form silver nitrate. This silver nitrate reacts with the dichromate ions to form insoluble red silver dichromate particles. This is a very strong indication we have authentic silver. We can wipe it off and you see the particles come off on the tissue. Okay let’s do this again but close up so you can see it better. There we go, now we wait. A drawback of this test is that it because it dissolves a small amount of silver it damages the otherwise pristine finish of the silver object. So you should run this test on an inconspicuous place on the object or use a scratching stone and scratch off a small quantity of silver from the edge. Usually the edge is less noticeable than a face. The test solution can be applied to the scratch marks to get the same result. Okay now you can see the red silver dichromate crystals precipitating from the solution. Let me wipe it. You can see the crystals on the tissue as well as unsightly damage to the silver surface. Okay so that is how it works with silver metal. Let’s try some non silver metals and see how they compare. First let’s try aluminum foil. As you can see the aluminum foil has no visible change. Aluminum metal is what somewhat resistant to nitric acid due to an effect called passivation. Any aluminum that does dissolve forms aluminum nitrate which is clear and doesn’t affect the color of the dichromate very much. Okay let’s try zinc. Interesting, zinc metal is reacting very quickly and vigorously with the nitric acid to form zinc nitrate. This in turn reacts with the dichromate ions to form yellowish green zinc chromate. Zinc chromate was actually used a pigment before it was discovered that it was highly carcinogenic and killing people with lung cancer from the dust. Now let’s try some steel from this solvent container. In case you’re wondering, the silver testing solution is very stable as long as you don’t let it evaporate and should last indefinitely if stored properly. So feel free to make up a batch and keep it handy for silver testing. As for the iron, you can see we’re getting more of a yellow brown spot. No hint of red like in silver. Let me do this close up so you can see it better. What we’re getting is a mixture of iron and chromium nitrates. We’re also getting nitrates of whatever other metals are in the steel. Now if you are making or buying silver test solution to test for silver. I recommend trying a whole bunch of metals as well as known pure samples of silver so you can get used to the subtle color differences. At first glance an inexperienced eye might not be able to tell a real silver spot from a steel spot. Additionally use other tests like magnetism and density to get further evidence of a metal’s identity. Okay let me try another precious metal, platinum. Now no moron in the universe will sell you platinum as fake silver, but I’m going to run the test anyway. Platinum metal is very inert as i’ve proven in my chemical resistance of platinum video. And even this solution of nitric acid and dichromate shouldn’t be able to affect it. At least i hope not. I bought this coin for this video and I intend to return it when i’m done. If it comes back damaged i might be on the hook for the value of the coin. Okay it’s been about five minutes and it still looks the same. Let me wipe it. Looks like absolutely no effect, platinum is totally immune to silver testing solution. Well that’s a big relief. Okay so that was how you make silver testing solution from nitric acid and a dichromate or a chromate salt. Thanks for watching. If you would like to support the continued production of science videos like this one. Please support the channel on patreon. Links are in the video description.

85 Comments

  1. Hey NurdRage are you going to make hydrogen peroxide in the future?. I know it is pretty simple to make sodium peroxide but going from sodium peroxide to hydrogen peroxide is another challenge. I think it involves sulfuric acid precipitation.

  2. Would a drop of Na2S solution with a drop of acid (HCl) on the silver metal turn it black? (Ag2S). Not sure if the in situ H2S is enough.

  3. What would this do to nickle or chrome plating?Would it react to gold plating and, thereby, react to gold plated silver?What about silver alloys such as assorted Sterlings, Vitallium and silver solder (silver, tin, lead being one of the more common ones)?

  4. Excellent work! This is very useful information for quick spot testing of materials and will be very helpful to me in the future. Many thanks Nurdrage, you are the best!

  5. what is the attachment you connected to the round bottom flask called that prevented back flow when you were producing hcl from NaHSO4 and NaCL?

  6. That platinum coin is sooo expensive 0.0 I'm currently into Copper Ingots Bullion 😂 I think copper will go up in price.

  7. Very useful video. We that follow precious metals know that the real price of silver, if gold is $1300, is around $80 an ounce. I behooves a person to have silver as a hedge for the hyperinflation that will hit when the US dollar is removed as the world reserve currency,

  8. "Welll, that's a big relief", said NurdRage. A big relief of a leaf on a platinum coin.

    Pun game too strong! ;___;

  9. This makes no sense, here i have a silver coin for you, oh let me check if its real silver, crap now its ruined : ')

  10. 1200 for that coin lol can see why you would still be a little worried even though you knew it shouldn't do anything

  11. I couldn't hep but think that if the coin WAS tarnished, the store would have some explaining to do about their "platinum" coin…

  12. Can you make a video on the Marquis reagent?

    I know what components are required to make it, but I'd like to see this style of video about it. I've already seen the one made by backyard scientist.

  13. I assume gold would also be unaffected and probably it wouldn't touch iridium either since not even aqua regia can dissolve that.

  14. I have sitting here a very old Chroming Solution containing Potassiumdichromate. How can I get rid of it, or even recover the Chrome?

  15. Platinum was once thought to be a coomon, useless metal, worse than precious silver, so in 16th century someone could sell you platinum as silver.

  16. If the rather expensive looking platinum coin had been damaged, you could have went back on the seller for a fraudulent sale on the basis of……..science!!!!! Thank you sir.

  17. So if a 'silver' coin is fake, what metal(s) would most likely be present in the fake instead? Is it usually zinc or iron, or is it some other metal? If the coin was chromium-plated, there'd be no reaction with the solution, right?

  18. Hello. Is there a chemically tested way to determine if we exist in a universe that is theorized as comprised of mostly dark energy ( not dark matter we know what matter is ) with 70% or so of this almost undetectable property everywhere around us,I was thinking (ouch) is banging particles at near light speed the way to go or perhaps chemically examined could provide an easier,cheaper result. Patron.PEACE…

  19. You showed the solution had no effect on platinum, but just out of curiosity what would that solution do to palladium? Also nothing?

  20. Why not just use a touchstone? Just rub what you know is the silver you want on the surface and then rub the mystery metal next to it. If the traces don't match, you know that the mystery metal is not what you want. It maybe silver, but it might be too pure or not pure enough or mixed with something you don't want like copper.

  21. Do you think you can recreate the green water in the Rio Olympic pools with a plausible mechanism? And maybe what it would take to clear it up?

  22. Just wanted to pop in to say how helpful these videos are for reference purposes when I inevitably forget to write the formula down and don't feel like trudging through forum bookmarks to find it. I've been going through all your old videos when I need a process reexplained to me.
    I can watch these three times and learn something new each time.

    …that probably says more about me, but oh well

  23. Ins't better the acquaregia? Using it we can even estimate what metal and silver concentration composes the coin..

Leave a Reply

Your email address will not be published.


*