1

Chemistry / Re: What things can block x-ray imaging at airport customs?

« on: 16/11/2013 21:15:48 »

I would like to send a bottle of liquid by post but it is forbidden in my country and Xray always catches my parcel.

Do you know how I could do ?

You should be asking yourself a few questions:
-- Why is it forbidden to send liquids by post? (safety issues: risk of breakage and spillage; airmail: will the item be transported by air at any stage, or risk of explosion from pressure buildup in a sealed container)
-- Is the liquid really being detected by Xrays? (remember that the postal service has dogs trained to sniff out drugs or explosives, and even if your liquid is innocent of either of these charges it is possible that it may be providing a false positive, or that dogs might be trained to detect other substances, e.g. alcohol)
-- Should you be checking the fine print of the postal regulations? (for example, in my country, Australia, it may be possible to transport small amounts of liquid provided that the bottle is packed in a much larger box in vermiculite, and that the postal service/courier is aware of the nature of the shipment)

2

Chemistry / Re: Plating with brass.

« on: 09/09/2013 22:56:50 »

God is an element?   []

To answer your more serious question, though, brass plating is simply not possible. If you used a brass anode, you might achieve either copper plating or zinc plating (depending on other conditions) but not both. Even hot dipping is problematic because of the volatility of zinc: A "safe" brass melt would not be hot enough to achieve good surface adhesion to a metal

3

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 17/07/2013 12:34:18 »

From Henry (reply #234):

Henry@damocles
clearly you are no chemist at all,
otherwise, you would have known that to make a standard solution of, say,  0.1 n NaOH,  you need to boil the DI water for 10 minutes to remove all CO2
so the reaction
HCO3 - (bi carbonate) +heat => CO2 (g) + OH-
is therefore quite correct, to describe what we are doing in the lab..
Since there are giga tons of bicarbonate in the oceans it follows clearly that (more) CO2 follows (more) warming.

umm... No, Henry! You are confusing two thermodynamic quantities here -- whether a reaction takes in or gives out heat (∆Hrxn = enthalpy of reaction) , and the direction of spontaneity of a reaction (∆Grxn = gibbs free energy of reaction). In most cases the reaction that gives out heat is the spontaneous one, but in this case the situation is reversed, and especially if you want to involve hydroxyl and bicarbonate! For the reaction that I described for solution/release of CO2(g) the ∆H°rxn is around -36 kJ/mol (i.e. energy released), but the ∆G°rxn is around +8 kJ/mol. Of course the activities of the various substances come into play in deciding the direction of spontaneity, but they have no part in the enthalpy change (and this post provides even more empirical evidence that you are not seriously a chemist).

From evan-au (reply #235):

I'm sorry, but I don't understand the use of a binomial fit to climate data. Please clarify.

I regularly use the Binomial Distribution, but I don't see how this relates to climate prediction.

Please provide some more information about how this curve fitting was done. The Binomial Distribution can provide a few curve shapes, based on a single probability parameter:
   •   Declining towards zero
   •   Increasing towards one
   •   A bell-shaped curve, which starts at zero and ends at zero, with a peak in the middle

Evan I think that what Henry means by "binomial fit" is a 2nd order polynomial fit (which guarantees a catastrophe in one direction or the other!) -- but I cannot be sure. Notice though how everything is expressed in terms of "last x years" so that his data remains firmly anchored on the last two years, which have both been La Niña years.

4

Physics, Astronomy & Cosmology / Re: Why don't people in Australia feel upside down?

« on: 17/07/2013 02:18:33 »

Ahhh.
So Atlas was Australian?

Atlas was a croweater: http://www.atlas.sa.gov.au

5

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 17/07/2013 02:00:15 »

from MoreCarbonOK:

true, I don't know much about computer science

and I do think you and me are good chemists, both of us qualifying in that direction.

I am afraid you lack my knowledge on statistics
which includes probability theory. Stats 1 is reasonably simple, stats 2 is difficult, stats 3 is more complicated
especially on sampling techniques, where you have to be sure of randomness and representative-ness,

but if you just grasped stats 1,  you would understand what I am saying

(1) As a good scientist, I believe in dispassionately following the evidence. The evidence that MCOK is a good chemist is totally belied by the fact that in earlier posts in this lengthy interchange MoreCarbonOK posted as follows:

Smokers do not die (immediately) from inhaling  near 100% CO2

The air which smokers inhale is roughly 15% CO2 at most. The point that BC was making in his next post, which would be transparent to a good chemist, was that the nitrogen component of air, 78%, is not involved in the combustion reaction. It is also a fact that oxygen continues to be necessary to support the smokers' lives.

from henry (moreCarbonOK):
Quote
Clifford,
are you a chemisdt?
Any (good) chemist knows that there are giga tons and giga tons of bi-carbonates dissolved in the oceans and that (any type of) warming would cause it to be released:

HCO3- + heat => CO2 (g) + OH-.

This is the actual reason we are alive today. Cause and effect, get it? There is a causal relationship. More warming naturally causes more CO2. Without warmth and carbon dioxide there would be nothing, really. To make that what we dearly want, i.e. more crops, more trees, lawns and animals and people, nature uses water and carbon dioxide and warmth, mostly.

Wake up out of your dream worlds. More CO2 is better. I hope you at least agree with me on that.


Henry are you a chemist? Any (good) chemist knows that there must be a stoichiometric balance in an equation system like the one you have been quoting so frequently to justify your simplistic assumption.

If the equation that you are relying on to account for the increase in atmospheric CO2 as the result of increasing temperature, then the alkalinity of sea water would be rising in accordance with the increase in atmospheric CO2. In fact it has been falling. This is more in line with the conventional explanation of a steady increase in atmospheric CO2 in line with human activity, with approximately one third of the additional CO2 burden being taken up by the world's oceans. An analysis of the global sources and sinks of CO2 also matches the conventional explanation: CO2 is mostly generated over land, and much more over populated industrialized land, and is mostly absorbed in the oceans. The models now have a fine enough resolution to pick out specific areas of ocean, e.g. the Behring Strait, where CO2 is being released to the atmosphere. But they are more than compensated for by the overall effect of the oceans in absorbing CO2. (By the way this has been confirmed by direct measurement).

Any good chemist should be able to do a simple calculation to show that the equation itself is far from correct as quoted:
HCO3^–(aq) + heat --> CO2(g) + OH^–(aq)
It should read:
HCO3^–(aq) <==> CO2(g) + OH^–(aq) + heat
Moreover it is closely linked with another step:
OH^–(aq) + HCO3^–(aq) <==> CO3^2–(aq) + H2O(l) + a little more heat
to provide an overall result of:
2 HCO3^–(aq) <==> CO2(g) + CO3^2–(aq) + H2O(l) + even more heat.

Provision of more heat should, on the face of it, result in the absorption of atmospheric CO2, although this will depend on the availability of aqueous carbonate.

(2) MCOK's claim to be well versed in statistics also appears, on the evidence, to be rather optimistic.
He says:

I am afraid you lack my knowledge on statistics
which includes probability theory. Stats 1 is reasonably simple, stats 2 is difficult, stats 3 is more complicated
especially on sampling techniques, where you have to be sure of randomness and representative-ness,

His sampling techniques might be spatially representative, but they are certainly temporally unfortunate, to say the least. Why? Because they are based on a cooling from a peak in 2002-3 to a trough in 2010-12. But the peak corresponds to an El Niño event in 2002-2003 declining to two consecutive La Niña events in 2011 and 2012. The corresponding ENSO indices can be found at http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ensoyears.shtml.
When the ENSO influence is removed from the (Australian) data, it is found that there is still a warming trend:
http://www.aussmc.org/documents/waiting-for-global-cooling.pdf

6

The Environment / Re: How will climate change alter ocean currents?

« on: 16/07/2013 04:29:20 »

Earth systems are enormously complicated, and we are only just starting to understand them. The problem is that there are both negative feedback (leading to regulation) and positive feedback (leading to amplification and chaos) loops in operation, and there is a very fine balance between them.

For at least the last half million years the climate appears to have been operating in a bistable mode -- relatively longer ice ages leading to relatively shorter interglacials. About 20 years ago there was a theory that the switching mechanism involved a change of ocean circulation when the sea surface temperature reached a certain level that shut down the Gulf Stream. The Gulf Stream is responsible for providing Western Europe with a milder climate than at similar latitudes in Canada or Russia. When the Gulf Stream shut down, glaciation started in Western Europe, and this tipped the balance of a positive feedback leading to extensive glaciation in the whole of the Northern Hemisphere.

I do not know the present status of this hypothesis, or even where it is documented, but if you are really interested I think a little web research (perhaps starting with "Ice Age cause" or "Gulf Stream ice age" as terms in a google search) should get you into it.

7

Physics, Astronomy & Cosmology / Re: Why don't people in Australia feel upside down?

« on: 14/07/2013 04:46:33 »

People often get lost in the outback when quite close to roads could this have something to do with the sun going round the wrong way ?

Yes that is part of the story. When I visited Britain some years ago, I got lost in Richmond Park because I assumed at 11 am that South would be to the left of the sun (as North is at home)

8

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 12/07/2013 02:16:37 »

From alancalverd (reply #220):

True, most of these disasters have been caused by a failure of the water supply or seriously bad science, but it's difficult to imagine how a few percent more foliage could be a Bad Thing. 400 ppm CO2 won't do you any harm, and it may just help to avert then next major agricultural catastrophe.

True, but it is also hard to imagine how it could be a good thing:

From damocles (reply #217):

11% greening in response to 15% CO2 increase over the same period is hardly unexpected in desert plants that are not water-limited in their photosynthetic response. Fact is that most plants, including over 90% of food crops, are water-limited.

Meanwhile there is an argument that more CO2 will lead to global warming, rising sea levels, and more erratic weather, which definitely is a bad thing. It is not an overwhelming argument, but it is a position supported by over 90% of the serious scientists working in the area, which at least means that it must be seriously considered by any rational person.

9

Chemistry / Re: What are the correct pronunciations and conventions for chemical terms?

« on: 09/07/2013 23:51:00 »

According to Chris (Reply # 6):

That cannot be right; the "3" should be on the same level as the O and is used to communicate the number of molecules or atoms of a chemical species; superscripts ahead of a species imply isotopes. There is no 3 isotope of oxygen, so that has to be wrong...

Technically chris is quite correct -- the spectroscopic notation should follow the molecular descriptor in parentheses. However chemists usually shorten the notation by a superscript in front of the molecular descriptor

(especially if they, like me, cannot remember whether the correct spectroscopic term for ground state molecular oxygen is triplet-pi-you or triplet-sigma-you-minus etc.!)
---
actually it is oh-2-parenthesis-triplet-sigma-gee-minus-close for the ground state, and oh-2-parenthesis-singlet-delta-gee-close for the excited singlet state.

www.rz.uni-frankfurt.de/~rsch/1O2-english.html‎

10

Chemistry / Re: What are the correct pronunciations and conventions for chemical terms?

« on: 09/07/2013 23:33:43 »

There is enough of a context in the text
"Under air conditions, ground-state oxygen molecules (3O2) are degraded by 185 nm UV to (ground-state) atomic oxygen O(3P), which then reacts again with molecular oxygen to generate ozone (O3). The ozone is degraded by 254 nm UV and becomes an excited oxygen molecule (1O2) and an excited oxygen atom (O(1D)). Therefore, continuous generation of AOS is possible through the generation of ROS and O3 by 185 nm UV, and the conversion of O3 to AOS by 254 nm UV. Since both the 1O2 and O(1D) are AOS, strong oxidizability is predictably generated by exposing a target to the AOS."
to enable a chemist to say with some confidence that it should be read "triplet-oh-two", "oh-triplet-P", "oh-3", "singlet-oh-2", and "oh-singlet-D"

11

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 09/07/2013 22:45:24 »

From alancalverd:(reply #213, following on from 211 and 212)

Just to quote a bit of the article that MCOK referenced:

Quote
In findings based on satellite observations, CSIRO, in collaboration with the Australian National University (ANU), found that this CO2 fertilisation correlated with an 11 per cent increase in foliage cover from 1982-2010 across parts of the arid areas studied in Australia, North America, the Middle East and Africa, according to CSIRO research scientist, Dr Randall Donohue.

“In Australia, our native vegetation is superbly adapted to surviving in arid environments and it consequently uses water very efficiently,” Dr Donohue said. “Australian vegetation seems quite sensitive to CO2 fertilisation.

11% hardly represents "greening of the Australian desert", especially compared to a 200+% greening associated with a few seasonal floods! The headline on the article henry linked is a blatant overstatement, and might well cause confusion in readers other than myself!
Especially in the light of a few nature documentaries that have recorded the spectacular blossoming of the Australian desert in response to recent floods.

11% greening in response to 15% CO2 increase over the same period is hardly unexpected in desert plants that are not water-limited in their photosynthetic response. Fact is that most plants, including over 90% of food crops, are water-limited.
 

12

Physics, Astronomy & Cosmology / Re: What is the correct definition of weight?

« on: 09/07/2013 10:33:36 »

From evan au :

Similarly, if we place an object on bathroom scales at the equator, and increase the rotational speed of the Earth, the object will appear to weigh less. However, we don't normally detect this effect, since the Earth retains a fairly steady rotation, and the oceans and the land of the Earth is already deformed into an oblate spheroid (the geoid) which takes the rotation of the Earth into account.

Unfortunately evan these two effects reinforce, rather than cancel -- being further from the centre of mass makes the object lighter at the Earth's equator, and so does the centrifugal force. An object is lighter at the equator than at the poles by about 1.3% (quick and dirty calculation that may be in error) which is easily detectable.
---
Addition:

It belatedly occurred to me that I could probably find polar and equatorial values of g tabulated somewhere.

The polar value is 9.851 m/s/s, while the equatorial value is 9.750 m/s/s, so the different between a polar weight (heavy) and an equatorial weight (light) is actually 1.0%

13

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 09/07/2013 10:22:48 »

Alan, the "recent CO2 greening of the Australian  Desert" is no such thing. It is a water greening based around a few successive seasons of exceptional rainfall in the centre. It is an extreme form of a phenomenon that is not unprecedented, and can probably be attributed to climate change, which may or may not be an indirect consequence of CO2 mixing ratio change.

There is a form of farming in Australia called "opportunity cropping". When there is an inland flood a lot of the lakes fill up. The soil becomes waterlogged around the lakes. But there is a significant zone in a ring around any lake where the soil has just the right moisture content to support a crop and not to bog the farm machinery. The following year that ring will be a little smaller, and it will gradually shrink in towards the lake until the soil becomes too salty. At that stage cropping is abandoned until the next flood.

14

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 08/07/2013 10:30:28 »

Hint to you alan: If animals generate energy by converting carbon to CO2, what about plants and microorganisms?

http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_organic_carbon-cycle

plants ~50%, microorganisms ~45%, animals ~5%

15

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 08/07/2013 07:09:58 »

From Alancalverd (#201)

Which would make the graph all the more mysterious. As the amount of sunlight increases, so does the amount of CO2!

***

From damocles (#183)

Quote from: alancalverd on 04/07/2013 09:45:03
Reverting to Mauna Loa, they do publish an annual CO2 cycle with the underlying trend removed.  I'm baffled as to why the CO2 level rises whilst the trees are growing, reaches a peak in summer, and decreases as photosynthesis shuts down.  When I was a lad, we were taught that photosynthesis extracts CO2 from the atmosphere, so I'd expect exactly the opposite behaviour if your model is correct (and they haven't moved Hawaii!). Where does the summer CO2 come from? Certainly not human activity, unless you Aussies have found some way of exporting your winter barbie smoke across the equator and halfway round the world.


Alan please check this diagram and tell me if that is the graph you are referring to: http://commons.wikimedia.org/wiki/File:Mauna_Loa_Carbon_Dioxide.png

If so, then you must appreciate two things:
firstly that the maximum and minimum are in May and October respectively, not June and December.
secondly that the amount of photosynthetic activity is reflected in the rate of change (slope) of the mixing ratio graph rather than the mixing ratio per se.

The months of maximum negative gradient (high photosynthetic activity) are June and July -- summer months -- while those of maximum negative gradient (low photosynthetic activity) are December, January, and February, the winter months.

***
Been there , done that, not really up for another lap!

16

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 07/07/2013 05:45:21 »

To summarize what we (i.e. the consensus of atmospheric chemists, with very few dissenting voices) know about atmospheric CO2: basically, there are three quite different effects.

(1) There is a well established and well understood seasonal pattern to the CO2 mixing ratio. It lags the insolation, its ultimate cause, by about 5 months. The chain of causality is mostly down to the extensive boreal forests in the cool temperate zone of the Northern Hemisphere:

insolation (maximum late June)
---> (lag of 0.7±0.5 months due to new growth coming on line)
photosynthetic activity (maximum mid July)
---> (lag of approximately 3.0 months because of 90° phase shift associated with time to achieve a minimum with a quasi sinusoidal rate of change)
CO2 mixing ratio minimum near boreal forests (mid October)
---> (lag of 0.7±0.3 months associated with thorough intrahemispheric mixing, Hawaii not being anywhere near the boreal forests)
CO2 mixing ratio seasonal minimum observed at Mauna Loa observatory (late October/early November)

(2) There is a rather less well understood lag of CO2 mixing ratio behind temperature by 50-300 years over the historical ice-core record of 4 ice ages and 4 interglacials in the last half million years, with ice age CO2 levels typically being around 200 ppm and interglacial levels being around 280 ppm. There have been several plausible hypotheses about why this should be the case, but it is a matter for continuing scientific enquiry.

(3) There has been a very steep rise in CO2 starting with the Industrial Revolution in Europe in the mid 19th century. It is certainly anthropomorphic. How do we know this?
• Because we can do carbon accounting and point to how the rise in atmospheric CO2 corresponds to consumption of fossil fuel
• Because if it were a natural effect then we would expect that it would be heralded by some extreme temperature rise, and this is certainly not in the temperature record
• Because it has taken CO2 mixing levels well outside the regime that has operated over the previous half million years or more, with CO2 levels varying between 200 and 280 ppm up to 400 ppm.
• Because there are much more subtle indications from isotope ratios that most of the additional CO2 burden in the atmosphere indicates that most of the increasing CO2 mixing ratio is coming from fossil fuels rather than living (i.e. recently dead) plants.

The fact that the recent rise in CO2 mixing ratio is anthropogenic is really a no-brainer!

17

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 06/07/2013 02:09:41 »

...{shrug}...

One last try:

Quote from: damocles on 05/07/2013 00:27:38
Please note that the CO2 level starts to decrease as the weather is warming up (May), and the decrease continues through the summer months (June through September).


not according to the inset on this graph
http://www.google.co.uk/url?sa=i&source=images&cd=&cad=rja&docid=XU7NI4a4HkIJlM&tbnid=AaQqiTlNR_JUkM:&ved=0CAUQjRw&url=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FFile%3AMauna_Loa_Carbon_Dioxide.png&ei=b2DXUey-N4ul0wXIhYGQCQ&psig=AFQjCNFFGFCI3UdKtRO6OD0LB_77meqJCA&ust=1373155780412660
which clearly shows CO2 increasing as the temperature rises to a maximum in May/June.

Firstly, the month of maximum CO2 is definitely May, not May-June. Secondly the months of maximum insolation are June-July, and the months of maximum temperature (in the region where the boreal forests are) are July-August.

My point is that photosynthetic activity correlates both with insolation and temperature (insolation is not such a good correlation as temperature, probably because new growth is still "coming on line" in early summer). What is involved in this correlation is actual temperature, not the amount of warming. But photosynthetic activity also correlates well with rate of CO2 reduction. That is, with the rate of change of mixing ratio, not the actual mixing ratio

18

Physics, Astronomy & Cosmology / Re: The definition of weight

« on: 05/07/2013 03:06:22 »

I have perhaps a smaller problem with the definition of "weight": If we define it as the mass of an object times the acceleration due to the gravitational force, then there is a problem with g -- it is obviously variable at different places on the Earth's surface, but should the value of g include the contribution from centrifugal force, or only the one from the differing polar and equatorial radii of the Earth? It seems to me that if we are working in a convenient Earthbound frame of reference, then we will want the former for some purposes but the latter for others.

19

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 05/07/2013 01:27:38 »

The months of maximum negative gradient (high photosynthetic activity) are June and July -- summer months -- while those of maximum negative gradient (low photosynthetic activity) are December, January, and February, the winter months.

Never mind the gradient, why does the CO2 level start below and increase above the trend level as the weather gets warmer? When trees become dormant they don't release more CO2 than they absorbed when active - indeed the release is negligible compared with the uptake, and in a closed system plants gradually absorb nearly all the atmospheric CO2 until there isn't enough to sustain growth. And as the weather gets warmer, humans discharge less CO2. So what is putting CO2 into the atmosphere as the sun gets higher in the sky? The annual cycle has been going on with the same amplitude and phase even when the underlying trend was much less steep than it is now. 

Seriously Alan? I do mind the gradient! Surely you can work out why from my explanation.
Please note that the CO2 level starts to decrease as the weather is warming up (May), and the decrease continues through the summer months (June through September). But it does not bring the mixing ratio to below par for a few months. Similarly when photosynthesis starts to shut down (October and November), the decrease tapers off and is soon replaced by an increase which continues through the winter (December through April) at a steady rate until the photosynthesis restarts the following spring (May)!
This explains the shape of the monthly correlation graph. It is not the mixing ratio that is linked to photosynthesis, but the rate of change of the mixing ratio!

As for the rest of your post, the effects you point out are totally valid, as are many other similar ones. But that is why climate scientists have made a very serious and detailed effort to eliminate them with model corrections and adjustments (in some cases) or by abandoning point measurements at ground stations in favour of satellite proxies (in others). But you dismiss those efforts as "bullshit"? Which side are you batting for? Or are you simply trying to change a scientific debate into a political one?

20

The Environment / Re: What is the meaning of 400 ppm (0.04%) atmospheric CO2?

« on: 04/07/2013 11:54:25 »

Australia is an extreme example of human habitation globally - practically everyone lives in a tiny strip around the coast and we have almost no useful historic data about the middle of any continent apart from Europe and even less about the oceans than cover 75% of the surface. That's the main problem with historic "data" - it derives from less than 1% of the earth's surface, and most of that very atypical.

Australia is the world's driest continent with the least reliable rainfall, and the leading nation with expertise on dryland farming. From very early times, the Bureau of Meteorology was faced with a significant problem -- how to reliably forecast significant rainfall and weather events. Every outback station has a rain gauge and most of them regularly send in rainfall reports to the Met Bureau. There is ample coverage of rainfall right across the continent. But temperature, wind, and barometric pressure is quite another matter. Weather stations were set up in remote locations quite early in the piece to fill in the blank spaces in order to have better data available for forecasting: a survey of the data at http://bom.gov.au will give station locations and the number of years for which data is available.

I think that you will find that the Americas have a similar coverage, although for South American countries the data might be incomplete or of questionable quality because of poverty and political instability.