# Tag Info

21

Circulated Coin I'll assume that the coin is circulated so a very gentle cleaning won't be a problem. You want to use some sort of organic solvent to loosen the glue, then very gently rub the residue off. You don't want to use any sort of silverware polish or anything abrasive when rubbing the coin. Good solvents might be olive oil or nail polish remover. ...

12

Well, $\ce{Ag2O}$ is just a basic oxide. As such, it would dissolve in suitable acids ($\ce{HNO3}$ would do), but I guess that's not quite what you want. Well, some metal oxides ($\ce{ZnO}$, for instance) are amphoteric and thus would dissolve in $\ce{KOH}$ as well, via formation of hydroxo complexes. Sadly, this is not the case with $\ce{Ag2O}$. Then we ...

7

A glance through the table of the isotopes in the venerable CRC handbook reveals that the longest lived radioactive isotope of Ag is $Ag^{108m}$, made by neutron capture by $Ag^{107}$. this has a listed half life of "> 5y", but the capture cross section is only $35\pm5$ barns, pretty small for thermal neutrons. So, it would be really hard to get a lot of ...

7

To give some numbers to MaxW's comment, you can see on this webpage the x-ray absorption energies of basically all the elements. For example, the K-edge of potassium is $3.61~\mathrm{keV}$. The L-II edge of silver is $3.52~\mathrm{keV}$ and the L-1 edge of silver is $3.81~\mathrm{keV}$. So, it seems like you are somehow automatically assigning the peaks and ...

6

I suggest to do the following: Line the bottom of a pan with aluminum foil. Put the silver piece on top of the aluminum foil. The silver piece and aluminum foil must be in contact with each other. To about 2L of hot boiling water add about a half cup of baking soda (Be careful!). Then add the mixture to the pan. Make sure to cover the whole silver piece. ...

6

Your choices are restrained as the precipitation of $\ce{SO4^{2-}}$ in $\ce{BaSO4}$ is the classical way to quantify the former and an electrochemical determination (in aqueous solution) is not practical. Electing $\ce{Ba(OH)2}$ may lead to the formation of silver hydroxyde, equally poorly soluble in water. $\ce{Ba(PO3)2}$ itself is very poorly soluble, as ...

6

Barium nitrate has a water solubility of $\pu{10.5g/100mL}$ at $\pu{25^oC}$. It isn't specified in the question what concentration of sulfate you suspect might be present, but given that you are trying to check for sulfate by precipitating with barium, barium nitrate should be the way to go.

6

To put the other answer in a graphical context, I took the X-ray emission spectra of K and Ag from some place online*, and plotted them together, crudely resized to fit the same scale. Some of the Ag L-lines (I think it's Lβ 1 and/or 2) are at exactly the same position as the K Kɑ line. So, the software sees a certain amount of counts at K, and identifies it....

5

The short answer is "no". There are materials, both actual and theoretical, which would have a higher conductivity, but not as a simple "material". They only make better conductors under very precise conditions. Since you specifically ruled out superconductive cooling I think we can also safely rule out materials that are a single atom thick as a ...

5

Graphene supposedly has higher conductance. The [...] resistivity of graphene sheets would be 10−6 Ω⋅cm. This is less than the resistivity of silver, the lowest otherwise known at room temperature. but it is not a compound - it is a homonuclear molecule.

5

Silver in silver oxide is no more oxidized than in $\ce{AgNO3}$. So you should ask yourself the same question earlier, even before the reaction. Yes, noble metals are somewhat resistant to oxidation. But still they can be oxidized, and thus can form compounds, of which $\ce{AgNO3}$ and $\ce{Ag2O}$ are the examples. Even gold can be oxidized, though that ...

5

Silver's pretty soft—it's possible to just scrape it off with a metal spatula or something. Also, not all of the silver deposits on the glass. You might be able to adjust the conditions of the reaction to make more silver precipitate into the liquid where it's easier to get at. You can, of course, redissolve the silver in nitric acid or the like. Since the ...

4

The precipitation reaction is: $$\ce {Ag+ + Cl- -> AgCl_{(s)}}$$ The next reaction is: $$\ce {AgCl_{(s)} +Cl- -> AgCl2- }$$

4

You would get silver at the cathode, and oxygen at the anode. Since silver is below hydrogen in the spectrochemical series,it tends to get reduced over hydrogen, similarly, since $\ce{NO3-}$ is above $\ce{OH-}$ , it tends not to get oxidised, therefore giving oxygen. $\ce{Ag+ + e- -> Ag}$ (at cathode) $\ce{ 4OH- -> O2 + 2H2O + 4e-}$ (at anode)

4

AgO (silver(I, III) oxide) is unstable and decomposes to produce $\ce{O2}$ in aqueous solutions. Hydrogen peroxide is thermodynamically unstable too and slowly decomposes to form water and oxygen. Decomposition of hydrogen peroxide can be catalyzed by different compounds, including transition metals (such as Ag) and their compounds. Probably, the silver (I) ...

3

Hydroxide is bad for this process. You will have additional problems if hydroxide anion is present. Silver cation reacts with hydroxide anion to form silver hydroxide, which spontaneously decomposes into silver oxide: \begin{aligned}\ce{Ag+ + OH-}&\ce{ -> AgOH}\\ \ce{2AgOH}&\ce{ -> H2O +Ag2O}\end{aligned} In addition to shutting down the ...

3

The energy in the electromagnetic radiation decomposes AgCl into its components, silver and chlorine. This produces finely divided silver particles, which look dark because yet solid silver (in the form of an ingot, for example) has a typical metallic 'colour', silver powder is dark.

3

If one needs to work with organic solvents, silver(I) oxide can be dissolved in trifluoroacetic acid (TFA) producing silver(I) trifluoroacetate $\ce{AgOCOCF3}$, which is a versatile reactant in organic synthesis (compact overview: [1]); also a precursor or chloride precipitant in the synthesis of metal complexes (see, e.g. [2]). References Wistrand, L.-G.; ...

3

Hydrogen halides are strong acids, meaning that their conjugate bases $\ce{X-}$ are extremely weak. Thus, adding $\ce{H+}$ will neutralize stronger bases such as $\ce{OH-}$ first before $\ce{X-}$.

3

Did find a source and the nature of reaction apparently involves some standard chemistry, surface chemistry, some radical activity and electrochemistry resulting, upon warming, in the demonstration of some yellow elemental sulfur! Here is a description of the reaction pathways, starting in alkaline conditions, surface chemistry on the Aluminum metal (which ...

3

Since the lab is past due now, I'll give what I think is the answer. $\ce{Ag2SO4}$ is somewhat soluble in water. It is most likely that you simply didn't get enough to cause precipitation. The other possibility, which I don't think applies here, is that you have a supersaturated solution. There are some precipitates for which crystals are just stubborn to ...

3

Is any one of these reaction more "true" (occurring more often naturally) than the others or is it the case that a little bit of everything is happening? I think the best answer is "a little bit of everything". Silver sulfide forms faster but requires exposure of the silver to sulfur-containing materials (like human skin, food, etc.). Silver that isn't ...

3

You can use hydrated tri-sodium citrate, it's readily soluble in water. As for its chemical reactivity, it's identical to tri-sodium citrate. You should take into consideration the increase in the molecular weight in the hydrated form due to the presence of water molecules.

3

When hydrogen peroxide is added to silver(I) oxide, it reduces to silver(here) $$\ce{Ag2O + H2O2 → 2Ag + H2O + O2}$$ Silver(II)oxide is unreactive towards hydrogen peroxide and hence it is a good method to separate a powder containing silver(I) oxide and silver(II) oxide.

3

The tarnishing of silver by sulfur is primarily due to hydrogen sulfide. Hydrogen sulfide is found throughout the Earth's lower atmosphere, and has many sources including the human body$\pu{^1}$. The amount of hydrogen sulfide naturally found in the air has been estimated as $\pu{0.11-0.33 ppb}$ ($\pu{0.15-0.46 ug/m3}$). Lower levels ($\pu{0.02-0.07 ppb}$;...

3

Have you tried olive oil? Smooth over surface of coin generously, leave overnight on a rag inside of plate to prevent seeping to anything you don't want oil on. The following day, use a microfiber rag to buff off the tape. Add a little more oil sparingly if needed while buffing. I had tape and adhesives from my old military bags get stuck to everything ...

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