John Cuthber

Hypervalent_iodine, perhaps the text of the email I just got from Greg will clarify that: it says "John Cuthber, Greg Boyles has sent you a new personal conversation entitled "Hello John". Greg Boyles said: ====================================================================== In the immortal words of Robyn Williams in Good Morning Vietnam. "You are in need of a **** *** more than any man in history" Anyway Greg, re "How can you be so sure that all silver tarnish is entirely silver sulfide?" I'm not. I never said it was. So you are straw-manning . Please don't. As has already been discussed it's quite likely that some of it is copper sulphide . However, at least some of it is Ag2S (as witnessed by the smell of H2S when you remove it with Al and soda). Unless you remove that you won't clean the silver. Silver oxide is, indeed, black Silver oxide is soluble in ammonia. The tarnish on the silver I tested did not dissolve in ammonia. Therefore it is not silver oxide. You were aware of those facts. You chose not to think things through before posting. As for the tub of hot ammonia, I remind you that this is a science forum. Unless you do the experiment you are just guessing (and your guess is at odds with the known facts and reasonable theories). And I'd still like to see your calculation for the solubility of silver sulphide in ammonia solution. Edited to censor Greg's naughty words.

I suspect it does quite a lot of damage. Unfortunately, here in the UK the government is planning to make it worse by removing one of the mechanisms by which such errors are found and acted upon. For example Mr Cameron says "You've got to look at the quantity of rules – and we're cutting them back; you've got to look at the way they're enforced – and we are making sure that is more reasonable; we're taking self-employed people out of whole classes of health and safety regulation. "But the key about health and safety is not just the rules, the laws and regulations – it's also the culture of fear many businesses have about health and safety." from http://www.telegraph.co.uk/news/politics/david-cameron/8994868/David-Cameron-vows-to-cut-back-health-and-safety-monster.html This is after the the guy who wrote the report http://www.dwp.gov.uk/docs/lofstedt-report.pdf that the same government commissioned said that "My overall conclusion is that there is no evidence for radically altering current health and safety legislation. This overwhelming view was expressed by a wide range of stakeholders including groups that represent employers. Furthermore there is evidence that work-related ill health and injury is itself a considerable burden on business (as well as a cost to society more generally) and that the regulatory regime offers vital protection to employees and the public." I suspect that politicians are the last people to notice their own lack of ability.

This bit " the diammine salts would undoubtedly remain stable." is just plain wrong. Even if you keep the lid on the sample the complex will still dissociate- the ammonia won't leave the solution- it just leaves the complex. Incidentally, at 80C most of the ammonia would boil off unless you were using an autoclave. This has no place in a sensible discussion about cleaning silverware. There are no practical conditions where you can wash the tarnish off silver with aqueous ammonia. The ozone is an interesting idea but most people don't have an ozone generator.

You seem to have misunderstood something I pointed out in a previous thread. Raising the temperature may well cause the complex formed by ammonia and silver to break up. Once the silver is "free" from the ammonia, it is more likely to react with sulphide ions and precipitate. It is entirely reasonable to suspect that the solubility of silver sulphide in ammonia solution will fall as the temperature rises. Do you actually have any data about this, or are you just assuming, in the face of the theoretical prediction, that you will be right? The effect of the concentration of the ammonia is already accounted for in the calculation which you haven't done. Please do so, I'm sure you will find it very informative. The effect of pressure will be very small because the change in volume is very small.

You move it so the sun hits it at 80 degrees rather than 90. Sin(80º) is 0.9848 It will receive roughly 985W. There is another factor- more of the light will be reflected from the steeply sloping surface so the efficiency drops more rapidly than the simple geometry would suggest. That factor depends on the material from which the cell is made etc- it's rather difficult to calculate. If I were you, I would ask the manufacturer how the angle affects the energy output.

Greg, Re "Now unless you can back up your position with a PHD and professorship in applied chemistry (I doubt it) then butt out!" please let me know what letters I need to put after my name that will make the silver sulphide decide to ignore the solubility data and dissolve in the ammonia? also, do you realise that the outcome of an experiment is a fact, not an opinion, so your saying "We are all well aware of your opinion." doesn't make sense. Anyway, to answer one of your questions, there's typically about 7.5% copper in silver used in jewellery etc. http://en.wikipedia.org/wiki/Sterling_silver re "If silver iodide, chloride and sulfide have varying solubility, albeit very low, in water then logically they would also have varying solubility in ammonia solution also, and probably at least slightly higher than in pure water. Which is to say that ammonia should be capable of dissolving some Ag2S varying with temp and conc of the ammonia." In the thread I cited earlier, I gave you the data to let you calculate that solubility at room temp and a reason why the dependence on temperature might not be what you expect. Have you calculated the solubility of silver sulphide in ammonia solution? If not, may I suggest that you do so before you speculate further?

And yet the silver wire I put in some ammonia back here http://www.scienceforums.net/topic/62131-cleaning-silver/page__st__20 is still black with sulphide. Of course, as I said before, that's exactly what you would expect from the published data on the solubility of silver sulphide and the strength of the complex that silver ions form with ammonia. Do you realise that something doesn't need to be true to be patented?

Sorry, have I missed something? If China was atheist in, say, the 15th C and Europe was theist then the discussion might have some point. What is being argued here is that one bunch of religious folks may, or may not, have developed "better" technology than another bunch. So what? If you can show me how a bunch of 15th C atheists did, that would be interesting. Anyway, I'm reminded of this

Meh! try England, we can have floods and a drought at the same time.

1. Without an afterlife (for which, I remind you, there is no evidence) they are the same. In both cases it's "conform or die". 2 I think that's nonsense, would you care to clarify it? 3 I could, but the end of the middle ages roughly corresponds with the start of science, so what would be the point? Incidentally I went to a middle ages University Oxford was founded very roughly in the middle of the middle ages . 4 If you can show me evidence then I will change my scientific beliefs. If you show a theist evidence that he is wrong- for example the moons of Jupiter or the scientific age of the world, you will be ignored, lied about or threatened. They will not change their belief. In that respect they do not want change. It's not absurd to say so. 5 to any extent that that statement is true, at least the scientist have evidence for the lack of a "why"- they looked and couldn't find any. The assertion without evidence that "there is a "why" because we believe in it" is absurd. In order to make any progress with that, you need to show that this magical "why" actually exists. 6 yes, fair enough, they read books about the book and books about those books too. A bit incestuous I think. 7 ad hom, not worthy of comment. 8 political correctness would require me to ignore the issues that Islam (and other faiths) raise. My point is about as politically incorrect as you can get. Please feel free to find out what the phrase means. And, if you want to know what moral guidance religion gives today in the West, have a look back to the story I cited in post number 64.

"Religion isn't inherently totalitarian," It offers you a choice; typically "believe or face eternal damnation and /or burning at the stake" whereas a totalitarian state like Stalinism offered a choice between "believe or get shot." Obviously totally different. "No it doesn't. It is religious institutions that built the very educational systems on which the modern world was built." "Even today many of the oldest and most respected universities in the world are religious institutions or built by religious institutions." This is a bit like saying that "cave men" built the original buildings so they are responsible for modern housing. A lot has happened in between. Certainly the original universities were places for the study of theology and the people there also learned other stuff, but none of this gets round the fact that religion wants things to stay the same, but science wants them to advance. When I was a student my old and well respected University still taught theology- but not to very many people. They became places of learning when they stopped studying one old book and looked at the rest of the world. BTW, an Islamic proscription of representational art doesn't help text-book writers any.

Unless you can tell me what oxidant you plan to use for step 5 ("Oxidise this resulting solution to produce Pr2 O(SO4)3(?)") you are talking nonsense. Also "you are no worse off than you were to begin with. " is only true if you don't value your time (strictly speaking, someone else's time) and didn't pay for the materials you wasted.

OK, so it's a stretch to think of this as "poverty" in the narrow sense, but let's remember that even now in the 21st c in the affluent West things like this http://www.bbc.co.uk/news/uk-england-london-16427840 are still done in the name of religion.

Why? It's not as if GX's question will ever matter in the real world.

"This is simply false. Religion and Science are tools to explain two completely different aspects of human existence." It would be fine if this were true, but nobody seems to have told the church about it. Galileo may have remained a Catholic? So what? that wasn't the issue. The problem is that the church banned his teachings. Doing so held up progress. If the Church stuck to the things that are not in the realm of science then it wouldn't have much to say would it? It doesn't provide a moral guide (if it did, how come our nominally Christian society ignores quite a lot of it. We really don't stone kids to death for swearing at their parents as Leviticus tells us we should.) It doesn't tell us about the origin of the universe- but it claims to. On the other hand religion, or it's spokesmen (and they are generally men), tells us that we shouldn't believe the evidence of our eyes if it contradicts their magic book. The fundamental distinction between religion and science is that science can admit to making mistakes. Because of this it doesn't need to imprison people for their beliefs.

In the end any confrontation will be with reality, and it's a lot less polite than me. I'd still like to know how you think the presence of the Nd will affect the oxidation potential of Pr.

As far as I know they work just fine. There's more detail here. http://en.wikipedia.org/wiki/Order_of_the_British_Empire

I'm not a Christian: I'm pretty staunchly atheist. But I do sometimes entertain the idea that the universe may have been created by a God who didn't know what He was doing. Something like the character Trelane in this http://en.wikipedia.org/wiki/The_Squire_of_Gothos

"Abstinence is the best form of birth control. I don't see how anyone could dispute that. " No it isn't, because it doesn't let you screw. Other forms of contraception do let you have sex and, since screwing is fun, they are better. Of course, any form of homosexual sex has a very low risk of pregnancy too, but the Catholic church isn't happy with that either. Fussy aren't they. To get back to somewhere near the topic, is there a link between poverty and religion. If so is it a causal link and if so which way does the cause go? Does religion, by, for example, proscribing contraception and therefore ensuring that families have a lot of children who they might not be able to feed properly, promote poverty. Does the diversion of effort to things like maintaining a religious class (of priests etc and their associated buildings, servants etc) deprive people of the opportunity to provide for themselves? Does this promote poverty? Does the suppression of knowledge (as in the inquisition, the story of Galileo etc) hinder the development of an educated society and thus rob that society of the best means to progress? Does this promote poverty? Does religion promote the hatred of others simply because they subscribe to a different faith (or none), and does this lead to conflict and war which rob society of wealth ,safety, liberty and life?

No, or at least not in the normal way of using one.

What for? You could always make it. http://en.wikipedia.org/wiki/Lime_kiln The stuff is difficult to keep (it reacts with H2O and or CO2 from the air) so it's generally made where it's needed.

Dleger13, do you realise that 95% of the world doesn't live in the US?

http://en.wikipedia.org/wiki/Salmonellosis

" this is a completely seperate issue, is it not, to dealing with separating all of the rare earths? " No, not really. Ce and Eu which have relatively stable oxidation states other than (II) are easily removed. All the others are difficult to split. Even if only two of them are present, the fact is that those two are still very similar and so it's hard to get either of them pure. "If you mean that the commercial extraction processes for the rare earths typically don't take out Pr with Ce, could this not be something to do with the influence of the so many other lanthanoids as are present in rare-earth ores, which aren't capable of being oxidised to a 3+ or higher oxidation state" How, exactly, does an ion know what other ions are present? Imagine a Pr+++ ion in solution wondering whether or not to be oxidised to Pr++++, is there some way where it can say to itself "Oh, I see there's some Ce(IV) over there- that will lower my redox potential"? (and incidentally, you seem to have your oxidation states muddled, they can all be oxidised to "+3 or higher" because they can all be oxidised to +3.) " Your point is valid only if the Ce is taken out first, then the rest of the rare earth elements are treated sepparetely." It is, so it is. Again, shouldn't you have checked? "Lastly, I've said all along that this is project is full of uncertainties" Exactly my point. There is no uncertainty. It won't work. It remains difficult to separate these two elements. I still don't think it's practical as a home experiment.