Timeline for Why isn't my electrochemical cell producing its potential voltage
Current License: CC BY-SA 4.0
16 events
| when toggle format | what | by | license | comment | |
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| Jan 13, 2021 at 14:36 | comment | added | Stack Exchange Supports Israel | @Maurice It was not clear that the sentence "the operation is forbidden by law" was only talking about high schools | |
| Jan 12, 2021 at 21:21 | comment | added | Maurice | @user253751. I was the President of the Swiss Association of Chemistry Teachers at the time where the law was started. Before this new regulation we could decompose $\ce{HgO}$ in our lectures. And we did it without problems. I had personally gone to the central office in Bern, obtained the support of the Swiss Chemical Society, discussed with clerks in charge of the new regulation. We have repeated the same argument that you are giving now to me. And still others. We had long discussions. There was nothing to do. No mercury in high schools (Gymnasium in Switzerland) ! | |
| Jan 12, 2021 at 18:32 | comment | added | Stack Exchange Supports Israel | @Maurice article 3 specifies a definition of "dangerous substances". It does not appear to list forbidden substances, nor does it contain an annex? The annex of the complete law merely specifies that it repeals a previous law. The law itself does not appear to ban any substances, either; it says they require approval before being sold. | |
| Jan 12, 2021 at 18:29 | comment | added | Stack Exchange Supports Israel | @MichaelHarvey then you should have specified school labs. | |
| Jan 12, 2021 at 9:55 | comment | added | Maurice | @User 253751...The following Chapter 3 is called Exceptions. In §3.1.c, it is stated that "the preceding interdiction does not apply if no substitutes of mercury is known for its use". When the law was introduced, our Society of chemistry teachers wrote to the authors of the text to be allowed to heat mercury oxide $\ce{HgO}$ in a test tube for showing in our lectures that both $\ce{O2}$ gas and droplets of elemental mercury are produced, and that nothing remains in the lower part of the tube at the end of the experiment. We got the answer that we should replace $\ce{HgO}$ by $\ce{Ag2O}$. | |
| Jan 12, 2021 at 9:49 | comment | added | Maurice | @User253751. I first would be pleased to know to whom I am writing. Anonymous name like yours does not prompt me to give you any answer. Second : My answer will last longer than allowed for an answer here. So tI will split my answer in two parts. let's go ! In my country try Switzerland, there is a federal law, dated 15. 12. 2000, named 813.1. and called "Law on chemicals" or LChim. The Annex 1. 732 of the Article 3, is Called "Mercury". Its Chapter 2.b states :" Is forbidden the use of elementary mercury, of compounds of mercury, and of preparations containing mercury". | |
| Jan 12, 2021 at 6:59 | comment | added | Michael Harvey | @user253751 - many things are banned in school labs but not others. | |
| Jan 12, 2021 at 1:06 | comment | added | Stack Exchange Supports Israel | @Maurice can I see that law? The law that says you aren't allowed to use mercury in your laboratory, ever? Or is it only when teaching? | |
| Jan 11, 2021 at 19:45 | comment | added | Michael Harvey | @Maurice - Mine also. There used to be a demonstration of a simple electric motor consisting of a star shaped sheet of metal rotating above a dish of mercury, between the poles of a horseshoe magnet. The points of the star dipped in the mercury. The current flowed from the battery to the centre of the star to the tips, via the mercury, and back to the battery. The star rotated and successive points dipped in the mercury. And out again, making a little spark. Not enough to hurt the students much, but sufficient to hurt the teacher during his or her career. | |
| Jan 11, 2021 at 19:34 | comment | added | Maurice | @User253751 In my country you cannot use mercury in chemistry lectures and in the laboratory. | |
| Jan 11, 2021 at 16:25 | comment | added | Stack Exchange Supports Israel | The operation is forbidden by law? I'm surprised to hear that it's illegal to mix two chemicals. I would expect that it's legal to mix them but then the law would be very picky about how you dispose of the mercury compounds - including the mercury dissolved in the aluminium, if it does that. | |
| Jan 11, 2021 at 7:31 | comment | added | Poutnik | @John Purely by the standard redox potential for $\ce{Ni(s)/Ni^2+(aq)}$, nickel should be quite reactive. The fact that it is not and is used in corrosion resistent alloys or metal platings says something. $\ce{ZnO}$ is probably not so compact and is quite soluble in acidic solutions. Note also that some standard redox potentials are more or less just theoretical equivalents of related standard reaction Gibbs energy and cannot be ( or just with difficulties ) directly measured, at least in simple scenarios. I have once seen redox potential for C/CH4 and would like to see its measurement. | |
| Jan 11, 2021 at 1:26 | comment | added | John | Thank you that is very helpful. In regard to the nickel electrodes would I be correct in assuming that nickel, like aluminum, also forms this instantaneous oxide layer? Also, would zinc then take longer to form this oxidation layer or is there some other explanation as to why its value matched the theoretical? | |
| Jan 11, 2021 at 1:16 | vote | accept | John | ||
| Jan 12, 2021 at 19:46 | |||||
| Jan 10, 2021 at 22:47 | history | edited | Maurice | CC BY-SA 4.0 |
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| Jan 10, 2021 at 22:19 | history | answered | Maurice | CC BY-SA 4.0 |