Greg Boyles

"Anyone will be get accepted from the group or not accepted. But TRUTH is one,which must & should be accepted by everyone. May be it came from any simpleseeing man".

 

 

 

What is your finalconclusion and what are your PERSONNEL views about GR.

 

 

For interest's sake.

How old are you and Anilkumar?

"Anyone will be get accepted from the group or not accepted. But TRUTH is one,which must & should be accepted by everyone. May be it came from any simpleseeing man".

 

 

 

What is your finalconclusion and what are your PERSONNEL views about GR.

 

 

Let me also point out to you and Anilkumar that the elastic membrane analogy for spacetime are exactly that.....an analogy and not a description of the nature of spacetime.

And elastic membrane is composed of matter and the spacetime is clearly not composed of matter.

The word 'fabric', that is often associated with spacetime, is merely borrowed from every day life and is not intended to describe the reality of sapcetime. Any fabric that we can perceive is composed of matter.

Perhaps space time is composed of something entirely different to the matter that we interact with every day.

Perhaps the fabric of spacetime is actually some sort of force field that resembles the magnetic force field that surrounds a magnet. A magnetic field can also be warped and distorted by other magnets and by electric currents etc.

Here you go Anilkumar, I saved you the trouble.

Here is Carl Sagan going through the flatland analogy as an explanation of how our 3 dimensional universe can be finite in size but boundless.

"Anyone will be get accepted from the group or not accepted. But TRUTH is one,which must & should be accepted by everyone. May be it came from any simpleseeing man".

 

 

 

What is your finalconclusion and what are your PERSONNEL views about GR.

 

 

The nature of the universe and of space is not determined by your or my opinion about it.

It is determined by the scientific process and by the mathematics behind it.

These are the only impartial means by which we can determine the truth about our universe.

The universe is not determined by trivial human politics and popular uninformed opinion.

As for me, I have an entirely open mind about it all.

While I do not pretend to understand the complex maths and science behind it, I can begin to imagine how it might be so. Again through the analogies provide by Carl Sagan and others.

I accept that space may be composed of some sort of 'fabric' that is warped by matter to create the force of gravity, even though I cannot perceive that fabric through my senses.

I do not accept that the dictionary definition of word 'space' is a universal truth of the space that exists between the planets, stars and galaxies.

The longer you spend trying to defend this silly idea the sillier you will look.

There are rather a lot of industry professionals who also seem to think that ammonia is able to clean the tarnish from silver John.

So perhaps you need to take a look at yourself and how silly you might seem.

There can not be two definitions of Space, whether given by the Science Dictionary or Modern Physics. [The English literary dictionary may have a slightly different or more descriptive meaning according to different contexts, but we are not concerned here.]

You are absolutely wrong mate.

Take a closer look at your dictionary. Many english words have multiple definitions depending on the conext in which the word is used.

Consider the word chief for example. It can mean a 'the head indian tribesman' or 'the main issue or concern' depending on the manor in which it is used.

Consider the word 'fruit'. In terms of botany a fruit is any structure that contains seeds. So pea pods, gum nuts, capsicums, egg plants, apples, bananas and tomatos are all types of fruit in a botany context.

But in a food context any fruit that does not have a high sugar content is refered to as a vegetable, i.e. cheffs regard a capsicum as a vegetable rather than a fruit.

Is the nature of space as defined by modern physics, any different?

 

What is the definition of Space according to Modern Physics?

So it is entirely resonable for the definition and contents of 'space' to vary depedning on whether your a refering to in a classic newtonian physics context or a quantum mechanics/particle physics conext.

The Neutrinos mentioned by you are contents of Space.

 

They or any other particles or objects inside the Space are not bodily parts or 'personal' parts of the Space. They are contents of Space.

 

The Space does not have any body, or any parts.

 

So we can not consider their properties as properties of Space.

 

The property of Space is 'It allows itself to be occupied'.

 

Matter can affect it only by occupying it.

 

It can not affect it in any other way by, like bending or warping it.

 

I am merely using neutrinos as an example of why, just because you can't see it or touch it does not mean that it does not exist.

I.E. Just because you can't see or touch the fabric of space time does not amount to evidence that a fabric does not exist.

Consider air. You can't see it or touch it unless a breeze blows. It conducts sound. It refracts light. And a solid object displaces the air when introduced to what you would regard as empty space.

The fabric of space time is similar. When a massive object is introduced it warps, rather than displaces, the fabric of space-time.

Look Anilkumar, at the end of the day I do not have any in depth understanding of warped space-time or the fabric of space-time any more than you.

We are talking about space-time being warped in the 4th dimension I believe.

But we are 3 dimensional creatures trapped within 3 dimensions, and all our perceptions and experiences are limited to those 3 dimensions.

The only way we can begin to understand this concept is through mathematics, which is certainly not confined to the 3 dimensional world in which we live our lives.

I comprehend very little of such mathematics myself.

But I can begin to comprehend how this stuff might be possible through a number of useful analogies that various scientists have come up with over the years.

Why don't you look au Carl Sagan's 2D flatland analogy that he used to explain how our universe is finite but boundless by being curved back on itself through a 4th physical dimension that is simultaneously at right angles to the 3 dimensions we know. It also explains how creatures that inhabit this 2 dimensional universe would perceive a 4 dimsional creature from another universe or reality.

It makes for compelling reading.

It was in his book Cosmos but I am sure if you look hard enough you will find it some where on the web.

If you can begin to see how a 4th physical dimension might exist even though you can't perceive it then the wiring in your brain may be reconfigured such that you begin to comprehend how 'space' might not be as 'empty' as we perceive it to be.

The one and only definition of Space is;

 

"Empty-vacant region/place/area/expanse/span (for lack of adequately expressive word), which permits itself to be occupied"

 

Nothing more, nothing less.

 

 

The fact mentioned by any knowledge seeking sector, that there is no AVAILABLE empty space, does not alter the definition of SPACE.

 

IF MATTER OCCUPIES SPACE; THERE HAS TO BE EMPTY SPACE IN THE OCCUPIED PLACE.

 

Kindly consider the fact that I have begun this thread to "comprehend the Spacetime curvature theory as proposed by GR".

 

I do not intend to be diverted into any other point of views like Consciousness, Reincarnation etc other than GR.

 

Thank you.

 

Edits: Italics

We are not talking about the dictionary definition of space, which is entirely irrelevant.

We are talking about the nature of space as defined by modern physics.

Hello Greg Boyles,

 

 

Please clarify, 'What ASSUMPTION is necessarily not valid'.

 

 

 

Are you proposing that;

 

whereas, 'empty Space' can not be warped, however 'occupied Space' can be warped?

 

 

'Anilkumar' your assumption is that the dictionary definition of 'space' is the only valid reality.

In actual fact the dictionary definition of 'space' is merely a convenience for classic newtonian etc physics, and in this context I guess that definition serves its purpose well enough.

But as I have previously stated there are countless neutrinos streaming out from the sun and passing through the space between it and the Earth.

When you look up at the sun some of those neutrinos pass through your eye ball, out the back of your head and through the Earth to the space on the other side. Neutrinos barely interact with ordinary matter so I believe from standard model.

You have no clue that this is going on. If neutrinos barely interact with matter, of which our bodies and eye balls are made, then there is no possible way that we can have senses to detect them and 'see' in neutrino 'light'.

But the physicists have detected them by means of a huge vat of bleach in a deep mine. Apparently neutrinos very rarely react with chlorine atoms and convert them to something else, and the scientists apparently have detectors sensitive enough to detect this.

So if there is a world of neutrinos right in front of your eye balls that you have no way of perceiving then what makes you so sure that space is entirely devoid of anything, other than matter which you can perceive easily.

Ho Hum.

I have two choices here.

I can believe the evidence of my own observation. The tarnished bit of silver wire is still sitting in the ammonia, and it's just as tarnished as it ever was.

Or I can believe the website you quoted as being "expert".

Call me cynical but since I see that what they are saying seems not to be true, I wonder why they are saying it.

Well, lets analyse what they are saying, and who they are.

The site is silversmithing.com.

It's the association of silversmiths.

What they say is "if your silver needs cleaning then we suggest you try soaking it in snake oil,and, if that doesn't work, sending it to use so we can charge you for the privilege of cleaning it."

Do you have any idea how long I agonised over deciding what to believe.

So, "That makes all your relative solubility of silver halides and silver sulfide effecting whether or not the silver can form complex silver ammino ions with ammonia a load of nonsense."

or it makes them mistaken (or worse), and the bit of wire shows which interpretation is correct.

 

"Well the experts seem to think that ammonia does take care all but severe sulfide based silver corrosion."

they are plainly not experts, if they were then I would have a nice shiny bit of wire by now.

So this

"If the sulfide corrosion is severe enough for ammonia not work then it is highly likely that the bicarbonate aluminium method will not remove it either and you would still have to get it done professionally. "

is also plainly hogwash, because it doesn't work with fairly mild tarnishing.

 

 

Incidentally, if you knew enough chemistry to comment usefully on this topic you would have looked up a few bits of data.

Solubility product: Ksp(Ag2S, 25 °C)= 6.69x10−50.

 

and

What is the Equilibrium constant of Ag (NH3) 2+?

Ag(NH3)2+ 1.67 x 10+ 7.223 stability constant

 

I will leave it to you to work out how those data (and a few sensible assumptions) explain why silver sulphide does not, and never will, dissolve in household ammonia.

 

Being stubborn is only good if you are right.

Perhaps your household ammonia is too old and has lost most of its strength or perhaps a small amount of heat would advance things.

I used ammonia to clean a corroded trailer plug with brass contacts, and I had to scrub them a little to dislodge some of the p[artially dissolved copper oxide/carbonate and get closer to the underlying metal. But no doubt if I left it for long enough and in fresher ammonia solution, or 0.88M ammonia which is easy enough to make, the carbonate/oxide would have dissolved without scrubbing.....eventually.

CHEMICAL CLEANING

The majority of silver objects recovered from archaeological contexts require only limited treatment. In most instances, the various corrosion products can be removed with simple chemical solutions (Plenderleith and Werner 1971:227-229). Common tarnish caused by sulfur compounds can be eliminated easily with commercial silver cleaning solutions. Alternatively, a mild silver dip solution that consists of 5 percent thiourea and 1 percent non-ionic detergent in distilled water can be prepared. A solution of 15 percent ammonium thiosulfate in distilled water with a 1 percent non-ionic wetting agent is stronger than the silver dip and is effective for removing both tarnish and silver chloride. For base silver with copper corrosion compounds, concentrated ammonia effectively cleans all copper compounds from the silver. Care must be taken, however, because ammonia dissolves silver chloride and will substantially weaken badly corroded silver. A solution of 5-30 percent formic acid in de-ionized water is effective for dissolving copper compounds without affecting silver chlorides. Formic acid can also be used to brighten silver that has already been cleaned with another chemical or technique. Metallic copper films can be removed with a silver nitrate solution. In general, however, simple washing in soapy water or rubbing the silver object with a mild polishing abrasive is usually sufficient.

First of all, ammonia added to your silver polish will remove some of the spotting far better than just using silver polish. I found this tip in a book of old formulas and it does work!

Perhaps standard household ammonia is generally to weak for use as a practical corrosion remover. But 880 ammonia is fairly easy to make or otherwise purchase.

Apparatus and chemicals

Eye protection for the teacher

 

Round- or flat-bottomed flask, 1 dm³ (see note 1)

Rubber stopper, to fit flask

Beaker (250 cm³)

Measuring cylinders (25, 100 and 250 cm³)

Dropping pipette

Glass rod

Access to a fume cupboard (for handling '880' ammonia solution)

 

The quantities listed below are sufficient for three demonstrations:

 

Silver nitrate (Corrosive, Dangerous for the Environment), 8.5 g

Potassium hydroxide (Corrosive), 11.2 g

Glucose (dextrose), (Low hazard), 2.2 g

'880' Ammonia solution (35% w/v) (Corrosive, Dangerous for the Environment), 30 cm³

Concentrated nitric acid (Oxidising, Corrosive), 100 cm³

Purified (distilled or deionised) water, 800 cm³

 

 

Technical notes

Silver nitrate (Corrosive, Dangerous for the Environment) Refer to CLEAPSS Hazcard 87

Potassium hydroxide (Corrosive) Refer to CLEAPSS Hazcard 91

Ammonia solution (‘880’ or 35% w/v) (Corrosive, Dangerous for the Environment) Refer to CLEAPSS Hazcard 6

Concentrated nitric acid (Oxidising, Corrosive) Refer to CLEAPSS Hazcard 67

 

Interesting huh John Cuthber?

Was reading and found that silver iodide wont dissolve in ammonia solution.

But I also found this that states that the solubility of silver iodide in water can be signficantly increased by heating the water.....pretty standard chemistry.

OK.....so what if you were to put your tarnised silver ware in 880 ammonia, in sealed container and raised the temperature a little.

Might just manage to push the reaction equilibrium in the the right direction so that it more effectively removes mild tarnish from the silver.

Best Answer - Chosen by Voters

_____Solubility and temperature

 

Ksp AgI at 25C = 8.3 x 10-17 = [Ag+][i-] = x^2 moles/liter

 

SOLVE for x

 

moles AgI = 1E-4 g AgI / MW AgI g/mole = ??

 

liter more water = [moles AgI / x moles/liter] - 1.0 liter = ??

 

ln (Ksp) = -dG/RT

 

SOLVE for dG

 

Ksp @ higher T = K2 = (0.001g AgI/MW AgI g/mole)^2

 

ln(K2/K1) = -- dG/R (1/T2 - 1/T1)

 

SOLVE for T2

 

Basic mathematics is a prerequisite to chemistry – I just try to help you with the methodology of solving the problem.

 

 

Source(s):

HBC&P 66th :

Solubility AgI = 2.8 x !0-7.27 @ cold water

Solubility AgI = 2.5 x 10-6.6 @ hot water

Thank you for clearing your view.

 

 

 

 

I suggest you to call 'nothing' as 'the place where we not see or we not experience anything'.

 

Anil, Now in science there is no consciousnesses about the question, what is space?

 

Some people say according to Quantum mechanics there is no empty space. All space is full of virtual particles and vacuum energy.

 

To get answer about space I had also started thread

 

http://www.sciencefo...occupies-space/

 

But we were not came to any consciousnesses.

 

Before we go to any conclusion. we must have to know, what is space?

 

 

 

 

 

 

 

Agree.

How can it be, when the space does not have any structure? Space is nothing but 'Vacancy'.

He is basing is failure to understand how space-time can warp on an assumption that is not necessarily valid.

If he was to accept that space is not necessarily empty simply because he cannot perceive or measure (yet) anything being present then he may be able to begin to understand how space time might be warped.

I concede that it "takes care" of silver suphide by saying that it doesn't really work "If the black corrosion spots remain, place the shaker back in and let stand for another ten minutes and inspect again. If the corrosion is not gone after 30 minutes, have the shaker professionaly refinished."

Well the experts seem to think that ammonia does take care all but severe sulfide based silver corrosion.

That makes all your relative solubility of silver halides and silver sulfide effecting whether or not the silver can form complex silver ammino ions with ammonia a load of nonsense.

Which makes you as stubborn as I concede I can be!

If the sulfide corrosion is severe enough for ammonia not work then it is highly likely that the bicarbonate aluminium method will not remove it either and you would still have to get it done professionally.

Thanks, gentlemen.

Perhaps I should re-touch the original post; my curiosity is around which of the proposed chemicals

-sodium carbonate

-sodium bicarbonate,

-sodium hexametaphosphate,

-sodium chloride,

-a combination of which,

-or another simple compound

 

does a better job in cleaning silver tarnish by sulphide, not by table salt

 

and/or optimal proportions of them to set aside what seems more empirical than science.

 

The original (and similar video) that triggered the use of this method maaany years ago is from Haley's hints :

----> http://www.youtube.c...h?v=Fg9skPKr5xc

 

And now, visiting my family overseas, water softener (sodium hexametaphosphate ?) is not available locally. So trying to do it with other compounds that could produce as good results as possible, reading other articles in the same subject there is opinions of other chemicals performing equally? well. Even found someone saying that ClNa alone also works ; and being the aluminium and heat the important items for the performance that transfers the tarnish from the silver to the aluminium.

 

Of course understanding the principle of the reaction is also interesting. Thanks again.

If you read that web page it states clearly that ammonia takes care of both forms of silver corrosion, the crsuted form caused by sodium chloride and the black form consisting of silver sulfide.

how do i mastering a programming language ?

Easiest way I have found is to obtain a working example program in a given language and fiddle around with it.

It also helps if you already know once computer language.

I managed to teach myself client side javascript very quickly by obtaining a working example of a shopping cart type website. Although the syntax and structure of javascript is almost indentical to C/C++ which I already knew.

I then modified it to suit my own website, including generalising the creation of items through appropriate functions rather than each item being stand alone code. Made modifying the structure of the webpages a breeze - simply by tweaking 2-3 functions rather than 20 individual items on each of 20 or so webpages.

Then I taught myself ASP programming and converted my shopping cart website to server side javascript. Wasn't to bad once I got me head around 'Response' and 'Request' etc.

Then I converted my ASP javascript to PHP so that my website could be hosted on a linux server.

Did all this in the space of perhaps 3-4 months.

If I tried to learn javascript, ASP and PHP purely from text books then it would almost certainly taken me a year or more to acheive all this.

Give it a try, it may work for you also. But if you don't already know a programming language then you will no doubt have to start off with some structured online tutorials to get yourself up to speed. Then perhaps you could try reverse engineering some working programs.

The following statements in your posts are factually incorrect

1 For example, silver chloride and silver sulphide salts are both insoluble in water,

but if you add enough ammonia (as in cloudy ammonia) these insoluble salts will dissolve to form Ag2(NH3)4S and Ag(NH3)2Cl.

2 So in other words ammonia is enough to remove the tarnish from both silver and copper based alloys.

3 As far as the formation of complex ions goes, it is irrelevant how soluble the simple salt is to begin with,

whether it is silver sulphide or silver chloride.

 

4 Ammonia would work at least as well as aodium bicarbonate if not better.

5 Silver carbonate is as insoluble as silver sulphide so I am dubious as to how effective it would be in removing tarnish anyway.

6 With ammonia, the silver ammino sulphide that is formed is completely soluble in water

7 For starters solid Al and insoluble Ag2S cannot chemically interact directly unless the Al was in the form of vapour.

8 Secondly, in preparation of this home made solution, the Al is already disolved in the bicarbonate solution before it is applied to the silver.

9 If this solution works then there is clearly some sort of ion substitution occuring between the Ag2S and the Na[Al(H2O)2(OH)4]

10 As far as I have ever known and according to this from Wikipedia there is NO distinguishing between the relative solubilities of silver halides -

they are all regarded as insoluble period.

11 John it is utterly impossible for the aluminium foil or the aluminium saucpan to reduce the silver sulphide to silver metal.

12 The only way that can happen is if the reductant (aluminium) is in solution.

13 So reduction of silver sulphide is CLEARLY not the mechanism here.

14 The only way that could happen is if the Al is in the form of vapour at extremely high temperatures, no doubt enough to melt the silver.

15 As far as I can see the H2S would not be generated directly by the process anyway.

16 So even if the silver reduction part of that equation is valid in terms of an electrolytic process,

the direct generation of H2S is not valid given that the electrolyte is alkaline.

 

 

Since, as you said " I was not familiar with the process until it was brought up in here."

perhaps you should have learned more and typed less.

And, btw, I'm sure that anyone who reads this will come to their own conclusion about to whom the phrase " Sorry buddy but your chemistry is some what 'rusty'. applies."

OK John, will you be gracious enough to concede that some of your assertions about ammonia were also factually incorrect.

http://www.silversmithing.com/care.htm

<A href="http://www.silversmithing.com/index.htm">

Silver Care

 

 

Salt Shaker Corrosion

 

 

Those crusty corrosion marks on and in your salt shaker can be a real annoyance. One way to avoid this problem from the very start is to empty the shaker after a dinner party and thoroughly wash it; this way the salt doesn't have time to do its damage. Heavily gold plating the interior is the only other way to preserve the finish because gold is impervious to the effects of salt. It is still wise to clean out the shaker at least twice a year and inspect the plate to make sure it has not been abraded by the salt.

 

There is a simple way to remove the corrosion yourself. Do this in a well-ventilated area and with nitrile gloves since you will be using ammonia. (Silver dips will not perform as well as ammonia.) If you are removing corrosion from a salt shaker, pour ammonia into a container, place the shaker inside, and cover the container. Let the shaker sit for ten minutes, then remove from the container and inspect. If the black corrosion spots remain, place the shaker back in and let stand for another ten minutes and inspect again. If the corrosion is not gone after 30 minutes, have the shaker professionaly refinished.

 

Just a thought. Could two universe's exsist in the same space? You know, over lap each other? And not even know it?

Isn't this what the bubble multiverse hypothesis is all about?

Our universe expands for ever at an ever increasing rate perhaps, but that the negative vaccuum energy of 'empty' space, or something to that effect, causes a new big bang/expansion some where in our space time vastly distant from us to create a new expanding universe that is inaccessible to us due to the 'untransitable' distance to it or due to the expansion of that universe or perhaps some other factors.

Is this roughly what the hypothesis is about?

"Well I did read something about semi covalent bonding between silver and sulphide ions in silver sulphide so you may actually be right in saying that the regular household ammonia is not strong enough to break that bond and dissolve the silver sulphide."

I'm right; not because you read something, but because I'm right.

The reason I know it's right is that I tried it.

 

 

"And by the way John......as far as dipping your silver wire in ammonia.......

 

Coke and ammonia removes the tarnish from 1c and 2c pieces, but you usually have to leave them in it over night to notice any difference."

Are these coins silver or is your point irrelevant?

 

The point is that your silver wire test, that you presumably conducted in response to my post, may be inadequate to draw the conclusion that it does not work.

Household ammonia works only very slowly on copper coins, as it would on tarnished silver, and you would need more than 5 minutes treatment to see if it really works or not on silver. Might also work better and a little faster if you heated the cloudy ammonia a little.

As for the Al foil bicarbonate treatment, I was not familiar with the process until it was brought up in here.

I can only go on what people have written about it online and clearly many of them are not properly educated chemists and don't really understand how the process works. Hence their documentation of the method is inadequate and does not credibly explain how it works to some one like me who is educated to some extent in chemistry.

That last website I found, where the silver and Al must touch, was the only one they gave me the clue that the process is electrolytic rather than chemical.

And as an basically educated chemist that reaction involving reduction of silver sulfide to silver metal does not make sense in terms of the way that the method is described on most websites I looked at. It only makes sense in terms of an electrolytic process which that chemical reaction gives no clue about. Electrolytic chemical reactions are usually represented by the seperate half reactions at each electrode and not by a combined chemical reaction.

As far as I can see the H2S would not be generated directly by the process anyway. Al would cause H2 to be released from the water as it dissolves and the sulphide ions would combine with the sodium ions in the bicarbonate. Sulphide ion is a weak base and a proportion would draw off H ions from water molecules to generates a small amount of H2S and leave behind more hydroxide ions.

The silver item forms the cathode and only one chemical reaction can occur at each electrode at a time. At the cathode it is reduction of silver ions. Generation of H2S at the cathode represents a seperate reaction that would require the combining of sulfide ions with hydrogen ions, however the electrolyte in this case is alkaline and contains hydroxide ions rather than hydrogen ions.

I know this because I used to make rotten egg gass bombs at high school - dust steel wool with sulfur dust and then set fire to it, this creates iron sulfide, then you soak this in a little dilute acid and small amounts of H2S are generated.

So even if the silver reduction part of that equation is valid in terms of an electrolytic process, the direct generation of H2S is not valid given that the electrolyte is alkaline.

Thank you for confirming the extent of your ignorance.

You may find this helpful.

http://chemed.chem.p...bp/ch18/ksp.php

 

Incidentally wiki does know that the solubilities of the chloride and bromide differ.

http://en.wikipedia....ubility_table#S

 

Perhaps the most important observation is that a simple experiment with some tarnished silver wire and a solution of ammonia has confirmed that you are wrong, the sulphide does not dissolve in ammonia.

I could post a picture if it would help.

Well I did read something about semi covalent bonding between silver and sulphide ions in silver sulphide so you may actually be right in saying that the regular household ammonia is not strong enough to break that bond and dissolve the silver sulphide.

But perhaps 0.88M ammonia might be up to the task, but I don't know for sure.

I did read that strong acids were capable of breaking the bond between Ag and S, although they do not form complex ions with Ag.

But clearly bicarbonate is not a strong acid.

Please post a valid chemical equation that explains how the aluminium reduces the silver ions, taking into consideration that in the afore mentioned cleaning solution:

1) That it is impossible for the Al atoms in the Al foil and the Ag ions in the tarnish to interact directly and that the Ag ions can only interact with Al ions once the Al foil has dissolved.

2) That you can't form Al(OH)3 in aqueous solution - it always forms sodium etc aluminate

Bayer process

From Wikipedia, the free encyclopediaJump to: navigation, search The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide).

 

Bauxite, the most important ore of aluminium, contains only 30–54% alumina, Al₂O₃, the rest being a mixture of silica, various iron oxides, and titanium dioxide.^[1] The alumina must be purified before it can be refined to aluminium metal. In the Bayer process, bauxite is digested by washing with a hot solution of sodium hydroxide, NaOH, at 175 °C. This converts the alumina to aluminium hydroxide, Al(OH)₃, which dissolves in the hydroxide solution according to the chemical equation:

 

Al₂O₃ + 2 OH⁻ + 3 H₂O → 2 [Al(OH)₄]⁻

2Al(s) + 3Ag2S(s) + 6H2O -> 6Ag(s) + 2Al2(OH)3(s) + 3H2S(aq) "

This is not a valid equation since the solid Al foil and solid tarnish are never in direct contact. The only way that could happen is if the Al is in the form of vapour at extremely high temperatures, no doubt enough to melt the silver.

And by the way John......as far as dipping your silver wire in ammonia.......

Coke and ammonia removes the tarnish from 1c and 2c pieces, but you usually have to leave them in it over night to notice any difference.

Thank you for confirming the extent of your ignorance.

You may find this helpful.

http://chemed.chem.p...bp/ch18/ksp.php

 

Incidentally wiki does know that the solubilities of the chloride and bromide differ.

http://en.wikipedia....ubility_table#S

 

Perhaps the most important observation is that a simple experiment with some tarnished silver wire and a solution of ammonia has confirmed that you are wrong, the sulphide does not dissolve in ammonia.

I could post a picture if it would help.

 

This

"John it is utterly impossible for the aluminium foil or the aluminium saucpan to reduce the silver sulphide to silver metal. The only way that can happen is if the reductant (aluminium) is in solution."

is obvious nonsense too.

If I put a nail in some copper sulphate solution the iron reduces the Cu++ ions to Cu metal.

If I do the same with a solution of silver nitrate I get metallic silver.

I can use Al instead of iron but, unless I remove the oxide film from the Al, it won't work very well.

One way to remove that oxide is to dissolve it in an alkali like hot sodium carbonate solution.

I might have to stand corrected here. Further reading about this bicarbonate/Al method reveals that the silver and the aluminium have to touch. So it appears that this process is meant to be electrolytic rather than purely chemical, as I have assumed from what I previously read about it.

So I was on the right track when I said reducing silver sulphide to silver metal would work if you made the silver item the cathode in an electrolytic cell.

In which case the afore mentioned reaction that I said was invalid could be appropriately split into the two seperate components (one at the cathode and one at the anode) such that it makes sense practically.

The seperate reactions would be something like this:

4Al(s) + 6H2O -> 6Ag(s) + 2Al2(OH)3(s) + 3H2 + 12e

6Ag2S(s) + 12Na-(aq) + 12e -> 12Ag(s) + 12Na2S(aq) "

This is usually the correct way of representing electrolytic chemcial reactions.

You don't seem to know what you are talking about.

The solubility of the original salt has a lot to do with whether or not the salt- say the sulphide- will dissolve in a complexing agent like ammonia.

As I said, silver iodide isn't soluble in aqueous ammonia, but silver chloride is. The complex formed is the same in both cases. The difference is that silver iodide is a lot less soluble.

 

The reaction does not make silver carbonate so the solubility of that salt is irrelevant. There was no reason for you to bring it up.

 

This bit of your post "Found this regarding the use if bicarbonate to clean silver. It apparently requires aluminium in the form of a saucpan or scrunched up foil. So there is more going on here that meets the eye. I am not familiar with complex ions involving silver and aluminium but this suggests to me that this is what is involved in the cleaning process here. I know that aluminium dissolves in alkaline solutions to form complex ions with hydroxide ions (generating H2 in the process)." shows that you have entirely missed the point of the reaction. The silver sulphide is reduced to metallic silver.

 

You say ammonia " Might do a quicker job if you combined the ammonia with a mild abrasive such as toothpaste.".

Did you watch the video?

It's not like the reaction is slow.

Silver halides, except for silver fluoride, are extremely insoluble in water.

As far as I have ever known and according to this from Wikipedia there is NO distinguishing between the relative solubilities of silver halides - they are all regarded as insoluble period.

John it is utterly impossible for the aluminium foil or the aluminium saucpan to reduce the silver sulphide to silver metal. The only way that can happen is if the reductant (aluminium) is in solution.

When the aluminium is dissolved in the alkaline bicarbonate solution the aluminium is already oxidized and has no further available electrons to dontate to the silver ions in the silver sulphide.....in order to reduce it to silver metal in a redox reaction. So reduction of silver sulphide is CLEARLY not the mechanism here.

It might work that way if you made the silver item the cathode is an electrolytic cell. with an appropriate solution.

Most tarnish removal involves removal of the silver sulpide, by means of an abrassive or via chemical means, to expose the underlying untarnished silver metal.

Sorry buddy but your chemistry is some what 'rusty'.

Anilkumar's question, and mine, is:

what is this grid made of?

If this grid is made of "nothing", then the analogy collapses.

You are only asking that because we are in a 3 dimensional universe and you have the benefit of a god's eye view of this analogy.

In the real 3D situation the 'elastic fabric' is itself 3 dimendional, we are also 3 dimensional beings and we are trapped within that elastic fabric.

The 2D analogy is far from perfect because it involves 2D space time but 3D objects. Perhaps if the objects were heavy disks on the surface of the elastic fabric rather than spheres it would be a little clearer. Or perhaps if you had two eleastic membranes with heavy disks sandwiched between them.

And how do you know that our space is made of nothing? That is merely our perception of it. And as I understand it, string theory mathematics etc tells us that it may not be totally empty as we perceive it.

What about the neutrinos that are streaming out from the sun in vast quantities. They only interact very weakly with the matter that our bodies (and planets etc) are made of. So here alone the space between the Earth and the sun is far from empty and yet our senses give us no way of perceiving that fact.

It would become obvious that if spacetime changes shape where you put the ball, the ball should change shape as well and become curved.

And if we are observers inside the ball, then we would also change shape.

IOW gravity could be considered as a force that makes matter change shape.

Constantly.

Well they probably do but my understanding of the concepts is largely limited to the analogies which don't cover those sort of fine details.

I'm a long way from sure that the ammonia complex is strong enough to dissolve silver sulphide.

It won't dissolve silver iodide and I think the sulphide is even less soluble than that.

Anyway, it doesn't actually answer the original question.

 

I have used the method given- I typically use a cup full of boiling water and a teaspoon full of baking soda (it fizzes when you dissolve it) then pour that into a glass bowl with the silver lying on a piece of aluminium foil.

 

It works very well and I don't think the amounts of salt or whatever are that critical. I think you just need fairly alkaline conditions.

It really is quite impressive the first time you see it.

As far as the formation of complex ions goes, it is irrelevant how soluble the simple salt is to begin with, whether it is silver sulphide or silver chloride.

Copper hydroxide and copper oxide etc are, to all intents and purposes, completely insoluble in water. But if you add enough ammonia all of them will dissolve completely.

Ammonia would work at least as well as aodium bicarbonate if not better. Silver carbonate is as insoluble as silver sulphide so I am dubious as to how effective it would be in removing tarnish anyway.

With ammonia, the silver ammino sulphide that is formed is completely soluble in water and hence can be rinced away totally with fresh water. Might do a quicker job if you combined the ammonia with a mild abrasive such as toothpaste.

Found this regarding the use if bicarbonate to clean silver. It apparently requires aluminium in the form of a saucpan or scrunched up foil. So there is more going on here that meets the eye. I am not familiar with complex ions involving silver and aluminium but this suggests to me that this is what is involved in the cleaning process here. I know that aluminium dissolves in alkaline solutions to form complex ions with hydroxide ions (generating H2 in the process).

<H2>What you will need:

• Aluminium pan or stainless steel pan and aluminium foil;
• Bicarbonate soda;
• 4 cups of very hot water;
• Extra water;
• White vinegar;
• Rubber gloves;
• Wooden spoon;
• Draining board;
• Polishing clothHow to...

</H2>1<H3 class=heading></H3>

Place cutlery in an aluminium pan. Add 1/2 cup of bicarbonate soda (also known as baking soda) dissolved in 4 cups of very hot water.

After a few minutes, wearing rubber gloves, remove the cutlery from the solution. If you need to use an implement, make sure it is wooden (do not use metal tongs).

I'm a long way from sure that the ammonia complex is strong enough to dissolve silver sulphide.

It won't dissolve silver iodide and I think the sulphide is even less soluble than that.

Anyway, it doesn't actually answer the original question.

 

I have used the method given- I typically use a cup full of boiling water and a teaspoon full of baking soda (it fizzes when you dissolve it) then pour that into a glass bowl with the silver lying on a piece of aluminium foil.

 

It works very well and I don't think the amounts of salt or whatever are that critical. I think you just need fairly alkaline conditions.

It really is quite impressive the first time you see it.

As far as the formation of complex ions goes, it is irrelevant how soluble the simple salt is to begin with, whether it is silver sulphide or silver chloride.

Copper hydroxide and copper oxide etc are, to all intents and purposes, completely insoluble in water. But if you add enough ammonia all of them will dissolve completely.

Ammonia would work at least as well as aodium bicarbonate if not better. Silver carbonate is as insoluble as silver sulphide so I am dubious as to how effective it would be in removing tarnish anyway.

With ammonia, the silver ammino sulphide that is formed is completely soluble in water and hence can be rinced away totally with fresh water. Might do a quicker job if you combined the ammonia with a mild abrasive such as toothpaste.

Found this regarding the use if bicarbonate to clean silver. It apparently requires aluminium in the form of a saucpan or scrunched up foil. So there is more going on here that meets the eye. I am not familiar with complex ions involving silver and aluminium but this suggests to me that this is what is involved in the cleaning process here.....assumung it does actually work.

<H2>What you will need:

• Aluminium pan or stainless steel pan and aluminium foil;
• Bicarbonate soda;
• 4 cups of very hot water;
• Extra water;
• White vinegar;
• Rubber gloves;
• Wooden spoon;
• Draining board;
• Polishing clothHow to...

</H2>1<H3 class=heading></H3>

Place cutlery in an aluminium pan. Add 1/2 cup of bicarbonate soda (also known as baking soda) dissolved in 4 cups of very hot water.

After a few minutes, wearing rubber gloves, remove the cutlery from the solution. If you need to use an implement, make sure it is wooden (do not use metal tongs).

Also found this:

I love this question!

 

The usual tarnish on silver is the black sulfide. The cool thing about this is that you can instantly remove the tarnish from any silver item with commonly available household items, and I do mean fast!

 

Aluminum is far above silver in the activity series for metals, and in a suitable solution will reduce the silver in the silver sulfide, reforming silver metal. The reaction is spontaneous and rapid in warm water:

 

2Al(s) + 3Ag₂S(s) + 6H₂O -> 6Ag(s) + 2Al₂(OH)₃(s) + 3H₂S(aq)

 

This might give some clues as to what is going on but it is impossible for this reaction to take place directly.

For starters solid Al and insoluble Ag2S cannot chemically interact directly unless the Al was in the form of vapour.

Secondly, in preparation of this home made solution, the Al is already disolved in the bicarbonate solution before it is applied to the silver.

Thirdly Al does not form solid Al2(OH)3 in alkaline solutions. Rather it forms the following soluble complex ion:

Al(H₂O)₂(OH)₄]^- (diaquatetrahydroxoaluminate). Hence the prepared cleaning solution would contain sodium diaquatetrahydroxoaluminate.

If this solution works then there is clearly some sort of ion substitution occuring between the Ag2S and the Na[Al(H₂O)₂(OH)₄]

Hi everybody,

 

How and why does mass curve space?

 

Thank you.

Unless you are fairly gifted at mathematics, I am not, then the best way you could begin to understand this is through the classic two dimensional analogy where space time is represented by a sheet of elastic material.

If you then place a bowling ball on that elastic membrane it creates a dent in it it. If you then introduce a marble on to the membrane it creates a smaller dent. If the marble shoots past the dent caused by the bowling ball then it may have its coarse altered due it it travelling part the way around the curve of the dent. Or the marble may travel in a circle around the dent due to it having a slower initial velocity and passing by the bowling ball at a closer range so that it falls further down the dent. This latter example represents a smaller body going into orbit around a larger body.

Of course the analogy is far from perfect because friction between the solid bodies and the elastic suface would prevent the marble from truly orbiting the bowling ball, rather the marble would roll down the dent and hit the bowling ball.

Hi.

 

A silverware cleaning method calls for a hot solution of sodium carbonate plus a 'pinch' of common table salt; or sodium bicarbonate, or sodium hexametaphosphate, and even plain table salt alone, all in an aluminium vessel.

 

The reaction is supposed to be

 

" 2Al(s) + 3Ag2S(s) + 6H2O -> 6Ag(s) + 2Al2(OH)3(s) + 3H2S(aq) "

 

But with so many choices as above, I have to think it is more a product of guessy empirism than a fine tuned fact.

 

Any solid suggestions and optimization please ?

Silver forms complex ions with ammonia. For example, silver chloride and silver sulphide salts are both insoluble in water, but if you add enough ammonia (as in cloudy ammonia) these insoluble salts will dissolve to form Ag2(NH3)4S and Ag(NH3)2Cl.

You can do the same thing with copper sulfate. Adding cloudy ammonia will initially in the copper ions precipitating out as pale blue copper hydroxide Cu(OH)2. But as you keep adding more ammonia, eventually it the pale blue precipitate starts dissolving as the mixture starts forming the complex ion Cu(NH3)4SO4 which is soluble in water and has a deep blue colour.

So in other words ammonia is enough to remove the tarnish from both silver and copper based alloys.

My logic was more along these lines:

 

Simple equations pop up in nature easily

Sequences related to exponentials can be generated by simple equations

If we want to avoid being mistaken for a natural event, we should avoid such sequences

 

Something else relevant:

 

Pulsars emit radiation on various bands in an extremely regular manner. There was some speculation when the first radio pulsars were found that they might be some kind of signal.

 

 

For something a bit more complicated/speculative, consider a pulsar that was losing rotational energy to its environment at a rate proportional to its speed -- something that happens in small scale phenomena, quite a lot. I don't know the exact situation for a real pulsar, and in our observations this process is very slow, but this is a plausible for the type of thing you'd see naturally (if not a specific example).

 

It would be governed by the equation [math]\frac{d\omega}{dt} = A\omega[/math]

Which has the solution [math]\omega = e^{At}[/math]

As such the time between the pulses would be a geometric series.(something along the lines of 1 2 4 etc, but more likely 1, 1.0324, 1.0324^2, and so on)

 

For anything more specific you'd probably have to talk to someone who does a lot of radio astronomy.

Pulsars emit an unvarying pattern of energy pulses. Even a pulsar whose rotation is slowing would not emit pulses that could not be interpreted as numbers.

A number sequence would require the pattern of pulses to be significantly irregular in same way so that it makes it possible to delineate one number from the next in the sequence. A slowing pulsar would not generate suffient irregularity as far as I can see.

Morris Code - nope lost me there (morse?) - the whole point of using primes is that we cannot at present see it as anything but artificial and with an intelligence behind it - most mathematical sequences could be natural

You all keep saying this, but no one has cited an example of any specific natural process generating any form of number sequence.

Some of you have only cited generalities like the 'number of tranmitters doubling' etc.

I am wondering about the causes of atmospheric pressure. All the sights I have found say that air pressure is caused by the weight of air above a point pressing down upon air below it. This seems to contradict Dalton's law of partial pressure because air cannot press on other air and have an effect. Am I missing something?

I was thinking that maybe gravity is more of the reason for the pressure, being that gravity is stronger closer to the core, so the weaker effect of gravity at higher altitudes could cause changes in air density or something. Could somebody help me understand this, please?

My understanding is as follows.

Due to gravity the closer you are to the surface the more tightly packed the air molecules are and the more collisions there between air molecules. More collisions = more presure.

Gravity acts like a container, confining the air molecules to a region. Although you could have equivalent pressure without gravity if you had the air molecules contained within a pressure vessel of some sort, e.g. a space ship.

Can someone clue me in as to what a type 1 immune response is?

 

It doesn't seem to be an official term, more like jargon that's used in an immunology lab. I"m having trouble finding any links for "type 1 immune response" that aren't related to type 1 diabetes.

 

Any help would be appreciated.

After refreshing my memory it is not type 1 and type 2 etc immune responses, it is more specifically type 1 and type 2 etc hypersensitivity.

Type 1 hypersensitivity is specifically mediated by IgE antibodies that bind to tissue mast cells and trigger them to degranulate. In so doing the release a variety of substances that trigger an inflammatory response - edema(sweeling), caplillary dilation(redening) and accumulation of neutrophils(pus formation)

This can be localised, e.g. after receiving some vaccines and mosquito bites or systemic, e.g. analphalactic shock.

It's not really about belief. Accepted scientific theories have loads of evidence to support them. They represent the most likely explanation.

 

Skeptical people don't accept anything as "proof", and most scientists are skeptical by nature. Theories are not proof, they just represent the best we know to this point.

 

On the other hand, when something has literal mountains of evidence to support it, like evolution, it's safe to say it's most likely the correct explanation. But since we haven't yet run every experiment we can imagine on every possible creature on the planet, we say that evolution is still a theory.

Important to note the difference between a hypothesis and a theory.

A hypothesis is a possible explanation for an unusual observation by a scientist. But it has not been subjected to the scientific process and ios therefore not verified.

A theory has been subjected to the scientific process and has been verified. But never the less it is still subject to review and ammendment if and when new data comes in that cannot be accounted for by the current theory.

For example DNA was unknown in Darwin's time and since its discovery the fine details of evolution have been ammended or added to in order to take into account the existence of DNA and its baring on natural selection.

Exponentials (I include both and the fibonacci sequence in this, as it can be described as the sum of two numbers, each raised to the same exponent) on the other hand pop up all over the place.

Can anyone provide a physics example, involving pulses of some sort of energy, of such sequences popping up?

There are a lot of things in science that I don't fully understand and take the word of the experts in the relevant fields.

But the film 'Contact' made a huge impression on me and now that I am reading the book, I would like to comprehend more fully the cosmic signficance of prime numbers.

I now understand the mathematics of them a little better, but to round off my understanding, I would like to understand how other number sequences I have mentioned can be generated by naturally. A concrete physical example rather than mathematical theory.