Chemical Resistance of Platinum

Chemical Resistance of Platinum


Warning: This experiment uses highly corrosive chemicals and produces toxic gases. This should be performed with gloves in a fume hood. Greetings fellow nerds. In a previous video we examined the chemical resistance of gold. In this video we’re going examine the chemical resistance of platinum. Here I have a one troy ounce bar of platinum metal. The first test will be in hydrochloric acid so I’m wrapping it in aluminum foil for comparison purposes. Here is the concentrated hydrochloric acid. I’m putting this round bottom flask over it to keep it from splashing out. What’s happening is the acid is reacting with the aluminum foil to form hydrogen gas and aluminum trichloride. Since it’s highly concentrated the aluminum trichloride hydrate is precipitating out as a powder. I’m going to add some water to completely dissolve it. And here is the platinum bar. Let me get it out of there. The hydrochloric acid completely destroyed the aluminum but the platinum bar is perfectly fine. Now for the sulfuric acid test. I have here some sugar and I’m adding to it some concentrated sulfuric acid. Let me toss in the platinum bar. And now we wait. What’s happening is the sulfuric acid is removing water from the sugar and leaving behind carbon. Now the platinum bar is embedded in this pillar of carbon so let me retrieve it. And there it is. Oh I think I scratched it when I jabbed it with my spatula. Oh well. The sulfuric acid itself did no damage to the platinum. Now for the nitric acid test. For comparison I’m also going to toss in a piece of copper. The nitric acid is reacting with the copper to produce copper nitrate and this brown nitrogen dioxide gas. Okay looks like the reaction is done. And here is platinum bar, completely immune to the nitric acid. Now for the reaction with molten sodium hydroxide. I’m putting these pellets on the surface and now I’m going to heat it with a torch. The sodium hydroxide is melting and as I continue heating it… oh look, it’s turning brown. Either the sodium hydroxide is turning brown or the platinum is. Let me let it cool and we’ll remove the sodium hydroxide to be certain. The sodium hydroxide is solidifying so we’ll need to dissolve it in water. Here we go. Looks like the brown color is permanent. Platinum can be tarnished by molten sodium hydroxide. What happened was under molten alkali conditions platinum is oxidized by air. So what we have here is a surface coating of platinum oxide. Anyway there we have it, platinum can be damaged by molten sodium hydroxide. For those interested, of course I’ll be dissolving this in aqua regia in a later video. Thanks for watching. In this video we’ll look at the chemical resistance of gold. In this video we’re going to dissolve platinum in a combination of nitric and hydrochloric acids, better known as aqua regia.

100 Comments

  1. I didn't mean to say refine, and yea, I know it doesn't. Someone told me the acid was worth more because it can be turned into elemental platinum or used in various things.

  2. Please find and play with HgO it could provide a theory for the die glock or " the bell " they say Germans used the red murcury for something please test

  3. I think he's confused with adding water to a strong base, such as sodium hydroxide. Now that is a bad idea.

  4. u forgot conc.nitric (100%) acid ! 🙂
    if u put water to it it decomposes into NO2 gas i know that you know that but just saying :p

  5. Ummm yes 100 percent nitric acid is indeed possible. Concentrated nitric acid is usually 98 or 97 percent but 100 is not impossible. 70 percent is the maximum concentration produced when the nitric acid forms an azeotrope with water.

  6. That bar had a serial number, therefore it was traceable and most likely to be real platinum, it is a safer war to buy a bar then a lump of platinum… SO, you do pay more for a nice bar (with serial number), then a lump of platinum (or even this bar who now looks fake when it has corroded, a thing platinum normally doesn't do…)
    So to conclude, you pay more for a nice bar because of the "insurance"…

  7. Cool video. Must be nice to be able to buy and essentially throw away platinum bars, considering how little of it there is in the world.

  8. Can you do some electrolysis of it?
    Also, you should have weighed it, before and after, to show that it doesn't lose mass.

  9. Hm, if you're trying to "compare" the reactivity of two metals with a given solution (Al and HCl, Cu and HNO3 vs Pt in those acids) why would you place them in the same beaker/solution? Even though Pt likely wouldn't have reacted much, if you place highly reactive Al/Cu with Pt the former will react leaving behind a fairly stable product. Essentially Pt will both have no time to react and *can't* be compared in reactivity because it isn't controlled/in its own beaker.

  10. Platinum is not just a very resistant metal, its actually a solid investment as well. If you haven't heard of precious metal investing start doing your research because your missing out on a lot of opportunity. 

  11. Platinum walks into a bar, the bartender says "we don't serve noble metals here." The platinum doesn't react.

    stolen from George Takei's FB*

  12. Could you clean off the platinum oxide using any of the concentrated acids you demonstrated in the video? Or would it not react?

  13. mr nurdrage i have a question for you i have a car battery that i want to open to get the lead out of it but im not sure what to do with the acid. so can i just put baking soda in it to neutralize it and if i can neutralize it with baking soda can i throw it down the drain ? after it been neutralized i mean 

  14. According to secondary school chemistry you can warm silver or gold in the absence of oxygen to remove oxides from the surface. I would guess the same is true of platinum. Whatever the method it wouldnt be difficult for such an inert metal.

  15. hi , am from indonesia…
    i've got 16 ounces troy platinum bar from my ancest, i want to test it in order to know it's fake platinum or not..
    can you tell me the simple way to test it,couse am not familiar with chemical stuff

  16. Happen to have a $1.5K bar of platinum?
    Drop it into all kinds of acids and corrosive chemicals then see what happens 😀
    And if you haven't been scammed, actually not much should happen of course, that's what noble metals are all about :p

  17. Hey NurdRage, would it be possible to do a video of the chemical resistance of Iridium? Or is Iridium too expensive to get a sample like you did with the Platinum Bar?

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