30641
Chemistry / Attention all Chemists! Urgent Help required...
« on: 21/03/2007 19:45:23 »
It mightt be an easier question, but I'm afraid I don't understand it.
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30642
Chemistry / Woolly question regarding Alum
« on: 21/03/2007 19:43:48 »
You will no doubt be pleased to know that you have the right stuff.
Part of the process of purification to get it up to European pharmaceutical grade involves crystallising it carefully. (Essentially a lot of the impurities don't fit properly into the crystal so they get left behind in the solution.) This gives a nice product but is expensive. For commercial materials like mordant there's less incentive to get it all that pure so they don't take so long crystallising it and get a crude powder.
Part of the process of purification to get it up to European pharmaceutical grade involves crystallising it carefully. (Essentially a lot of the impurities don't fit properly into the crystal so they get left behind in the solution.) This gives a nice product but is expensive. For commercial materials like mordant there's less incentive to get it all that pure so they don't take so long crystallising it and get a crude powder.
30643
General Science / How do they measure the carbohydrate content of milk
« on: 20/03/2007 22:10:24 »
"But I would have thought that carbohydrates represents a range of molecules covering quite a range of molecular weights? If that is so, how could you uniquely identify carbohydrates through chromatography?"
In milk there are not many different carbohydrates so it's not difficult. The question isn't any different from the general question of how do analytical chemists measure anything in anything and the (OK I realise this is rather unhelpful) answer is by doing analytical chemistry. In this case one possible answer would be to couple the outlet of the chromatographic column to a mass spectrometer. The other thing that is commonly done is to run chromatograms of known compounds for comparison.
"Do all humans gain the same energy value from the same carbohydrates, or do different people's digestive systems obtain differences in efficiencies in digesting carbohydrates?"
In the particular cases of milk carbohydrates the answer is no. Anyone with lactose intolerance will not only fail to gain any calories from the lactose in milk but will suffer ill effects from it. On the other hand broadly speaking, all people gain about 4 Calories a gram from any carbohydrate that is digestible. Cellulose is listed in nutritional information as fibre rather than carbohydrate.
In milk there are not many different carbohydrates so it's not difficult. The question isn't any different from the general question of how do analytical chemists measure anything in anything and the (OK I realise this is rather unhelpful) answer is by doing analytical chemistry. In this case one possible answer would be to couple the outlet of the chromatographic column to a mass spectrometer. The other thing that is commonly done is to run chromatograms of known compounds for comparison.
"Do all humans gain the same energy value from the same carbohydrates, or do different people's digestive systems obtain differences in efficiencies in digesting carbohydrates?"
In the particular cases of milk carbohydrates the answer is no. Anyone with lactose intolerance will not only fail to gain any calories from the lactose in milk but will suffer ill effects from it. On the other hand broadly speaking, all people gain about 4 Calories a gram from any carbohydrate that is digestible. Cellulose is listed in nutritional information as fibre rather than carbohydrate.
30644
General Science / How do they measure the carbohydrate content of milk
« on: 19/03/2007 19:49:55 »
They might measure the cabohydrates by chromatography. It wouldn't be very difficult.
30645
The Environment / Biofuels and climate chage
« on: 17/03/2007 11:50:10 »
Global warming is, it seems, a fact. There is more CO2 in the air than there used to be. At least some of that increase is due to industry.
What is less clear is that there is a causal relation between these data. Historic records show that it has been warmer in the past and also that it has been colder in the past. We survived and so did the polar bears. These changes took place long before mankind was making any difference to CO2 levels.
There are a lot of people whose jobs rely on funding of research into greenhouse gas emmisions. It would be odd if they didn't write "more work is required in this field" at the end of every paper they wrote.
Whether or not burning oil and gas contributes to global warming it would be prudent to reduce our consumption simply because these are finite resources.
The argument that even if there is no link between CO2 and global warming we should negotiate international treaties to reduce CO2 production fails to take account of the damage that such treaties may do to standards of living in the developing world. Those last 2 statements are not contradictory. Here in the Western world we have access to technology that can reduce our dependence of fossil fuels. That technology and infrastructure simply isn't present in the developing world. Whatever your stance on nuclear power, it's fair to say that the rich West is better placed to build reactors than the developing world.
BTW
John Redwood was known as Mr Spock, but only by people who were being nice to him.
What is less clear is that there is a causal relation between these data. Historic records show that it has been warmer in the past and also that it has been colder in the past. We survived and so did the polar bears. These changes took place long before mankind was making any difference to CO2 levels.
There are a lot of people whose jobs rely on funding of research into greenhouse gas emmisions. It would be odd if they didn't write "more work is required in this field" at the end of every paper they wrote.
Whether or not burning oil and gas contributes to global warming it would be prudent to reduce our consumption simply because these are finite resources.
The argument that even if there is no link between CO2 and global warming we should negotiate international treaties to reduce CO2 production fails to take account of the damage that such treaties may do to standards of living in the developing world. Those last 2 statements are not contradictory. Here in the Western world we have access to technology that can reduce our dependence of fossil fuels. That technology and infrastructure simply isn't present in the developing world. Whatever your stance on nuclear power, it's fair to say that the rich West is better placed to build reactors than the developing world.
BTW
John Redwood was known as Mr Spock, but only by people who were being nice to him.
30646
Chemistry / Explosive Urine
« on: 17/03/2007 11:22:19 »
Bleach reacts with urea to give nitrogen and CO2 (mainly) the bubbles of gas rising through the bleach carry the odour of bleach into the air so that you get a really strong pong. There are also traces of chloramines produced which are very irritant to the eyes and nose. On the whole it's a good idea to flush the bleach away before taking a leak.
Bleach will react with acids used for removing limescale and this will produce chlorine and this sometimes causes problems when people mix cleaning products.
On a slightly more weird note I once read of someone working in a lab many years ago where one of the jobs was to analyse urine samples from people working in some bit of the nuclear industry. They were looking for contamination by uranium and plutonium and the technique was quite simple. Dry down a sample of the urine in a dish, heat it to burn off the organics etc and check the ash with a geiger counter.
One day they made a strange observation. The urine sample from one person turned greed as it was dried down and then it exploded. The poor bloke doing the analysis repeated the experiment with the same result- this person really had got explosive urine. It turned out that he had been taking a cough medication containing perchlorate and this was being excreted via the kidneys.
I just can't help wondering about the lab technician having to go to his boss and explain what caused the bang.
Bleach will react with acids used for removing limescale and this will produce chlorine and this sometimes causes problems when people mix cleaning products.
On a slightly more weird note I once read of someone working in a lab many years ago where one of the jobs was to analyse urine samples from people working in some bit of the nuclear industry. They were looking for contamination by uranium and plutonium and the technique was quite simple. Dry down a sample of the urine in a dish, heat it to burn off the organics etc and check the ash with a geiger counter.
One day they made a strange observation. The urine sample from one person turned greed as it was dried down and then it exploded. The poor bloke doing the analysis repeated the experiment with the same result- this person really had got explosive urine. It turned out that he had been taking a cough medication containing perchlorate and this was being excreted via the kidneys.
I just can't help wondering about the lab technician having to go to his boss and explain what caused the bang.
30647
Chemistry / Monosodium Glutamate....Why need it ?
« on: 17/03/2007 11:10:22 »
I can't say I have checked but I wonder if cheese flavour crisps (made with real cheese and hence not suitable for vegetarians) have a shorter shelf life than "beef" flavour (totally artificial and vegetarian). In the case of crisps I think they are so dry that preservatives are not an issue (the salt may help with that). My best guess is the shelf life is determined by the fats going rancid. But anyway, you are right it's never simple and it is the consumer who makes the choice.
(BTW, I thought that inflation was down to the money supply and was therefore comletely in the hands of the government anyway)
(BTW, I thought that inflation was down to the money supply and was therefore comletely in the hands of the government anyway)
30648
Physics, Astronomy & Cosmology / How Do You Measure The Weight and Mass of A Star /Planet/ Thing ?
« on: 17/03/2007 10:58:46 »
For the great pyramid I think measuring it's size to get a value for the volume and then calculate the mass based on the density of the rock it's made from would be the best bet.
If I wanted to weigh a star I think I'd hope there was something in orbit round it. From the period of the orbit and it's radius I think you can calculate a mass.
If I wanted to weigh a star I think I'd hope there was something in orbit round it. From the period of the orbit and it's radius I think you can calculate a mass.
30649
Chemistry / The thickness of a bubbles ' wall !!
« on: 16/03/2007 21:50:59 »
You could get the average thickness by weighing it and calculating from the bubbles diameter and the density of the solution. The film is thicker at the bottom so you would need something more sophisticated to get a true picture. Interferometry would do. Spiking a dye into the solution would let you follow the thickness by light absorbtion.
30650
Chemistry / Monosodium Glutamate....Why need it ?
« on: 16/03/2007 21:36:43 »
"Quite surprised just now to see MSG as a flavour enhancer in a packet of crisps (US-Chips).
I mean...why do they put it in ?..why use it at all in any type of food preparation ?...are the flavours not strong enough ?..if not..then why use a flavour enhancer ?...why not just use stronger/more flavours in the first place ?
What exactly does MSG do ?...does it effect the food or MY ability to taste it ?"
The simple answer is money. It's cheaper to put MSG in food than to use real ingredients to produce flavoursome food.
MSG is a flavour enhancer in the same way that salt is and it has similar effects so yes, it alters you.
Of course the traditional aproach might be to add parmesan cheese or soy sauce- both great sources of MSG.
I mean...why do they put it in ?..why use it at all in any type of food preparation ?...are the flavours not strong enough ?..if not..then why use a flavour enhancer ?...why not just use stronger/more flavours in the first place ?
What exactly does MSG do ?...does it effect the food or MY ability to taste it ?"
The simple answer is money. It's cheaper to put MSG in food than to use real ingredients to produce flavoursome food.
MSG is a flavour enhancer in the same way that salt is and it has similar effects so yes, it alters you.
Of course the traditional aproach might be to add parmesan cheese or soy sauce- both great sources of MSG.
30651
Chemistry / Attention all Chemists! Urgent Help required...
« on: 16/03/2007 19:46:32 »
a
Diamorphine would certainly hydrolyse to morphine but I don't know how quick that reaction is. It would be markedly pH dependent.
b
I can't think of any legal source of those compounds apart from prescribed heroin.
c
I can't think of any source of acetyl morphine apart from heroin and its degradation products.
c (again)
Narcotine will not convert to morphine or any of its derivatives
d
You could look at this and see if you want to spend money on the papers
http://www.google.co.uk/search?sourceid=navclient&ie=UTF-8&rls=GGLJ,GGLJ:2006-33,GGLJ:en&q=%22hydrolysis+of+diamorphine%22
I think your friend may do better if he can show that the surface may have been contaminated by someone else without his knowledge. For example if it was at his house, did he ever host a party at which some "friend of a friend" or gatecrasher may have spilled heroin that he didn't clear up fully?
Diamorphine would certainly hydrolyse to morphine but I don't know how quick that reaction is. It would be markedly pH dependent.
b
I can't think of any legal source of those compounds apart from prescribed heroin.
c
I can't think of any source of acetyl morphine apart from heroin and its degradation products.
c (again)
Narcotine will not convert to morphine or any of its derivatives
d
You could look at this and see if you want to spend money on the papers
http://www.google.co.uk/search?sourceid=navclient&ie=UTF-8&rls=GGLJ,GGLJ:2006-33,GGLJ:en&q=%22hydrolysis+of+diamorphine%22
I think your friend may do better if he can show that the surface may have been contaminated by someone else without his knowledge. For example if it was at his house, did he ever host a party at which some "friend of a friend" or gatecrasher may have spilled heroin that he didn't clear up fully?
30652
Chemistry / Periodic table
« on: 11/03/2007 13:30:45 »
This reminds me of a thought I once had.
Imagine that you have a neutron star with some utterly huge number of neutrons. Add a single proton. Do you now have the nucleus of some absurdly heavy isotope of hydrogen?
Imagine that you have a neutron star with some utterly huge number of neutrons. Add a single proton. Do you now have the nucleus of some absurdly heavy isotope of hydrogen?
30653
General Science / why does "skin" form on my cup of hot chocolate?
« on: 11/03/2007 13:20:45 »
If someone really proves that chocolate is good for you I might have to revise my policiy of atheism. [
]
]
30654
General Science / Why are cooling towers shaped the way they are?
« on: 10/03/2007 21:29:05 »
Water vapour is less dense than air so wet air should also be less dense.
30655
Chemistry / Hydrogen Peroxide
« on: 07/03/2007 20:25:33 »
Lightarrow, What's the Italian for H2O2? (It's never going to make any real difference to me but I just wonder).
30656
General Science / How fast does a magnet attract ?..and other magnet questions !
« on: 07/03/2007 20:22:23 »
That electromagnet would have an inductance so you could only change the current through it at a finite rate; how do you define the time from "switched off" to "switched on"?
30657
Chemistry / Potatoe salt, sea salt, regular salt, LO salt..what's the difference ?
« on: 07/03/2007 20:15:32 »
No, but I thought about it when someone recently complained about their cartoon with GM sheep which had been modified not to emit methane. The cartoon pictured some very uncomfortable looking inflated sheep floating in mid air on strings like balloons. The person who wrote in was grumbling about the fact that methane is heavier than air so the methane filled sheep wouldn't float. He then pointed out that he was a diver so he knew about gases and things.
Last time I checked Methane (RMM 16.04) was markedly less dense than air (RMM about 29).
I understand thatdivers typically work a "buddy" system. I hope he gets his buddy to check his gas mixtures.
Anyway, it's time I thought of a signature too.
Last time I checked Methane (RMM 16.04) was markedly less dense than air (RMM about 29).
I understand thatdivers typically work a "buddy" system. I hope he gets his buddy to check his gas mixtures.
Anyway, it's time I thought of a signature too.
30658
Just Chat! / How do u think of absolutely nothing?
« on: 07/03/2007 20:07:27 »
I commend you all for being polite about any of a number of famous figures. Surely the answer to the questions "how do u clear your head so your thinking of absolutely nothing?..." is "I don't know - ask George Bush" (Or Tony Blair or....) []
It's an interesting question on a number of levels. Is it actually possible- are those who claim to empty their minds truly doing so or do they just not notice what their minds are doing?
Why would anyone want to completely clear their mind of all thought. And come to think of it, Zwitterion, why do you?
Assuming this is a real phenomenon, how was it discovered? What was someone trying to do when they found out about this? (BTW, that last question also applies to meringue)
]It's an interesting question on a number of levels. Is it actually possible- are those who claim to empty their minds truly doing so or do they just not notice what their minds are doing?
Why would anyone want to completely clear their mind of all thought. And come to think of it, Zwitterion, why do you?
Assuming this is a real phenomenon, how was it discovered? What was someone trying to do when they found out about this? (BTW, that last question also applies to meringue)
30659
Chemistry / Potatoe salt, sea salt, regular salt, LO salt..what's the difference ?
« on: 07/03/2007 19:56:18 »
Feel free to use it as a sig, I'd be quite flattered and I can assure you that it's my own composition. Nobody else would ever take the trouble to put "potato salt" into an anagram engine. Of course someone, perhaps Slartibartfast, might have been looking for an anagram of "Tattoo Alps".
Yes, I'm a fairly avid reader of PE.
Yes, I'm a fairly avid reader of PE.
30660
General Science / Creationist Challenge (proving the existence of light)
« on: 07/03/2007 19:43:18 »
In the style of many theological arguments.
The properties of "mindreading" are those properties that, in the experiment detailed above, would make it indistinguishable from light but in some other ways (only revealed to the chosen ones) differ.
Anyway, as we agreed, the real point is that science never really proves anything- it just disproves as many alternatives as it can.
Since the properties of "God", like those of mindreading, can be changed arbitrarily, "God" can never be disproved. Even where the properties of "God" are logically impossible, logic is deemed to be at fault.
For example "God" is, more or less by definition, omnipotent- He can do anything; that's what makes Him "God".
OK, can He set Himself a task which He cannot achieve?
If not then He's clearly not omnipotent. If He can set such a task then, since He can't achieve it He's not omnipotent. Omnipotence is a paradox, but that doesn't bother some people.
The properties of "mindreading" are those properties that, in the experiment detailed above, would make it indistinguishable from light but in some other ways (only revealed to the chosen ones) differ.
Anyway, as we agreed, the real point is that science never really proves anything- it just disproves as many alternatives as it can.
Since the properties of "God", like those of mindreading, can be changed arbitrarily, "God" can never be disproved. Even where the properties of "God" are logically impossible, logic is deemed to be at fault.
For example "God" is, more or less by definition, omnipotent- He can do anything; that's what makes Him "God".
OK, can He set Himself a task which He cannot achieve?
If not then He's clearly not omnipotent. If He can set such a task then, since He can't achieve it He's not omnipotent. Omnipotence is a paradox, but that doesn't bother some people.