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 1 
 on: Today at 02:46:19 AM 
Started by Gyvfdc - Last post by P
If you still haven't died in 3 days time then I think you will be OK.   ;)



 2 
 on: Today at 02:34:37 AM 
Started by Gyvfdc - Last post by Gyvfdc
Hi
Yesterday me and my friends were having a bit of fun in the chemistry classroom and one of my friends' shoe ended up in my bag. I did not think anything of it at the time, however later at lunch I noticed, that it had come in contact with my lunchbox. However I just brushed it off and ate my lunch. The problem is that afterwards I got really afraid that the shoe might have picked up some contaminants since we were in the chemistry classroom. I don't know whether i'm just overthinking it, but I would really like a second opinion.
Thanks in advance

 3 
 on: Today at 01:15:09 AM 
Started by angel01 - Last post by angel01
how decompose CO2

 4 
 on: Today at 12:56:00 AM 
Started by fahad jamil - Last post by rahils
1. We measure steam flowrate in kg/h for small flowrate of tph for bigger flowrate. The kg/cm2 is the steam pressure, not the flowrate.
2. However, pressure can indirectly measure flowrate, depending on piping configuration of system
3. For example, you have fixed orifice plate downstream

 5 
 on: Yesterday at 11:59:30 PM 
Started by kriggy - Last post by rolnor
If you have some DMAP as catalyst you probably dont need heating.

 6 
 on: Yesterday at 09:57:50 PM 
Started by kriggy - Last post by kriggy
That looks pretty cool.
So, the acid azide is just heated with amine to get the amide?

ah I see, with heating I get the courtious rearangement, not that this wouldnt be interesting as well, to get some urea derivatives there

 7 
 on: Yesterday at 12:57:08 PM 
Started by stickle - Last post by wildfyr
Pirahna solution? Highly dangerous but would fit the bill.

We don't know what polymer it is, and without FTIR or some manufacturer info we probably never will. If its polyester then KOH would be great. If its polypropylene then its useless.

 8 
 on: Yesterday at 11:40:56 AM 
Started by gumusonur - Last post by Enthalpy
Hypochlorite is excellent to kill bacteria. So-called percarbonate is a safer compound with about the same effect, also available in supermarkets.
https://en.wikipedia.org/wiki/Sodium_percarbonate
https://en.wikipedia.org/wiki/OxiClean and competitors
As you know from house cleaning, bleach without rubbing leaves the films in place, just sterilised.

 9 
 on: Yesterday at 11:18:02 AM 
Started by stickle - Last post by Enthalpy
Dissolving a polymer thicker than a paint layer tends to take very long. Nice if it works, but often discouraging. Ultrasound, like in a jewellery cleaner, often helps.

==========

An alternative might be an acetylene+oxygen torch. The flame burns the plastic away quickly, more so with an excess of oxygen. It may melt the coins too, depending on how it's done, but the silver in the coins has often the same value as the coins.

Molten silver is just more difficult to sell than a silver coin. Such a coin is basically a stamping meant to guarantee a silver amount and purity.

If you try the torch:
- Blow pure oxygen once the plastic burns. The flame will be less hot than with acetylene.
- Do that outside! Nearly all burning plastics are toxic for real.
- Maybe air suffices.

==========

Possibly a strong ultraviolet source would degrade the plastic at interesting pace, so it can be broken and brushed away, but I doubt it. Sunlight takes its time, especially if the plastic is black, thick, and resides between the coins. Some sources, like arc lamps, are stronger.

==========

As most chemical methods get slower with the plastic thickness, it wouldn't be bad to first separate the coins with a chisel, hammer (and vice), leaving just thin plastic on them.

After that, just a barbecue fire followed by brushing may suffice. De-oxidising the tarnished silver is standard practice.

==========

Hey chemists, would there be some compound (A bleach on steroids? Ozone? Percarbonate?) that oxidises the plastic away? That should be faster than a dissolution.

Or one that makes the plastic fragile (again an oxidizer?) so it can be hammered and brushed away?

Would a strong base be worth trying? Breaking the polymer chemically must be faster than dissolving it.

 10 
 on: Yesterday at 10:43:01 AM 
Started by trio - Last post by Enthalpy
Could it be that 2g/L H2SO4 count only the fraction that does not come from CuSO4?

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