francium

Francium, the fabled element at the bottom of group 1 and the most reactive of the alkali metals (if you are not familiar with the reactivity of group 1 metals, have a look at the video elsewhere on this site).

However, the truth is a little more boring. Francium is vanishingly rare and is found only as very small traces in some uranium minerals. It is the most unstable of the 92 naturally occurring elements and as it is so radioactive that any amount formed would quickly decompose into other elements. Although there are about 20 known isotopes of the metal only Fr-223, with a half life of 22 minutes, occurs in nature. There is estimated to be only ever about 20-30 g of the element present in the earth's crust at any one time and no weighable quantity of the element has ever been prepared or isolated.

Bad news for those of us hoping to see what happens when you put it into a basin of water.

Francium was discovered by Marguerite Perey, who worked as an assistant to Marie Curie, in France (from which the element takes its name) in 1939.

an inconvenient truth

Some of you may have seen 'An Inconvenient Truth' and be aware of Al Gore's involvement as an alarmist in the global warming argument. However, as good scientists we should always try to have a balanced view based on the provable facts available, and whenever possible arrive at this view independently of politics.

To see how much you really know about global warming take this quick test.

global warming test

If this has opened your eyes a bit and you want to find out more, have a look at this site.

icecap

methane bubbles

If methane gas is forced through a mixture of water, glycerol and washing up liquid, some rather flammable bubbles can be produced. Anyone got a match?

rocket trolley

New and improved, this time using a low friction trolley.

quantum santa

OK, so the last post wasn't good news for us believers, but what if Father Christmas was a macroscopic quantum object?

In his book, Unweaving The Rainbow, Richard Dawkins boasts that he tried to tell a six year old child that Father Christmas didn't exist. His argument was that Father Christmas would not be able to climb down all those chimneys and tiptoe noiselessly to the bedsides of hundreds of millions of children, all in one night. There simply wouldn't be enough time, even if reindeer were hypersonic.

Well, apart from being a somewhat cruel thing to do to a small child (the distinguished professor for the public understanding of science should pick on someone his own size), the argument is, to be charitable, an incomplete explanation. Dawkins may be no slouch when it comes to evolution, but he knows (by his own admission) rather less about physics.

Of course Father Christmas exists, and he can visit arbitrarily as many children has he pleases in as short a time as is convenient, barring mid-air reindeer pile-ups. The reason is that Father Christmas is a Macroscopic Quantum Object.

Let me explain. It is a feature of the quantum world that particles - such as electrons - can be in more than one place at a time, provided that nobody is watching. In a famous experiment known as the "two-slit" test, physicists have been able to fire a single particle at an opaque plate with two separate slits in it. The diffraction pattern seen on the other side of the slits suggests that the particle passes through both holes at once and interacts with itself. However, if detectors are placed at the slits, to see which slit the particle passes through, the diffraction pattern disappears, and the particle can be seen to pass through either one slit or the other, but not both. The key lies in the fact of observation. Provided that nobody seeks to measure the effect with more than a certain amount of precision, the particle keeps all its options open. But if someone looks too closely, the particle makes its choice. In the language of physics, its quantum wavefunction collapses.

Now, let's think of Father Christmas as a particle, obeying the rules of the quantum world. Following the logic of the two-slit experiment, it is perfectly possible for him to visit all the good children of the world simultaneously, provided that he does so unseen. If he is spotted, his wavefunction will collapse and he will be revealed as your Dad with a comedy beard after all. The quantum nature of Father Christmas explains the taboo against seeing him do his job - which Dawkins does not explain.

But there's more. It is possible to object that Father Christmas is far too large, rubicund and jolly to be a particle. In the real-life, macroscopic world of people, elves and flying reindeer, the quantum behavior of each of the squillions of particles from which we are made averages out, so what we see is the everyday phenomenon of causes preceding effects, and people who can never be in two places at once.

Cynics might attribute this last consequence to the deficiencies of Railtrack, but it is a fact that real people, even bearded men with red hats and big boots, tend to be found in discrete locations, irrespective of whether they are being watched or not.

This objection doesn't wash, however, because it is possible to have macroscopic quantum objects that are larger than single particles. Scientists have managed to choreograph large clusters of atoms to behave as if they were just one particle, in a kind of nanoscopic Busby Berkeley routine. Admittedly, these clusters are too small to see with the naked eye, let alone qualify as cheerful red-faced men with sacks full of gifts, but the point is made. Importantly, these macroscopic quantum objects observe the rules of the quantum world when cooled to within a whisker of absolute zero - minus 273 C. Any warmer than this, and the choreography breaks down and the clusters behave like any old bunch of atoms.

Nevertheless, in this frigidity might lie an explanation for another feature of Father Christmas that Dawkins neglects to explain - the undeniable fact that Father Christmas traditionally inhabits cold places, such as Lapland or the North Pole. OK, so neither of these places gets as chilly as absolute zero, but it must count for something that no deserving child would address their wish list to hot places such as, say, Borneo or Brazil. The very idea is quite ridiculous. QED (which stands for Quantum Electrodynamics, obviously)

the physics of santa

We all still believe in Father Christmas don't we? With Christmas fast approaching, time to take a closer look at the work of the big man, just to see if it really is possible that he might actually exist.

1. There are approximately 2.5 BILLION children (persons under 18) in the world. This is based on the World Population Consensus of 2000 and using the US's basis of 42% population under 18. However, since Santa does not visit children of Muslim, Hindu, Jewish, or Buddhist religions, this reduces the workload for Christmas night to 33% of the total, 825 MILLION (according to the World Population Reference Bureau). At an average rate of 2.5 children per household worldwide, that comes to 330 MILLION homes, presuming, of course, that there is at least ONE good child in each household, not a real safe assumption, but...

2. Santa has a total of 31 hours to work with, thanks to the different time zones and the rotational speed of the earth, assuming he travels from East to West, a safe assumption. This works out to about 3000 visits per second. This is to say that for each Christian home with a good child, Santa has just under 1/3000th of a second to park the sleigh, hop out, jump down the chimney or mist through a door or window, fill the stockings, distribute gifts around the tree, eat whatever snacks the good children have left him, get back up the chimney or back out the door, jump into the sleigh and get on to the next house. Assuming each of these 330 MILLION stops is evenly distributed around the landmass of the world (which we know is false, but accept to make the calculations simpler), we are now looking at about 0.78 miles per household; a total trip of 258 MILLION MILES, not counting bathroom breaks and watering the reindeer stops. This means that Santa's sleigh MUST move at about 8.3 MILLION MPH or 2,300 miles per SECOND – 3000 times the speed of sound. For purposes of comparison, the fastest manmade vehicle, Voyager II, moves at a pokey 39 miles per second, and a conventional reindeer can run at best 15 miles an HOUR.

3. The payload of the sleigh adds another interesting element. Assuming that each child gets nothing more than a medium sized Transformer© set of about 2 pounds and a small Sponge Bob SquarepantsTM hand puppet, the sleigh is carrying over 825 THOUSAND TONS, not counting the fat man himself. On land, a conventional reindeer can pull only 300 pounds. Even granting that these special reindeer could pull 100 times the normal amount, the job would take 36,000 reindeer. This, of course, increases the payload, not counting the fat man, another 54,000 tons, or roughly 7 times the weight of the QEII, the largest cruise ship on earth.

4. 880,000 TONS traveling at 2,300 MILES PER SECOND creates an enormous air resistance – this would heat up the reindeer in the same fashion as a shuttle re-entering the atmosphere. The lead pair of reindeer would absorb 32 QUINTILLION (32,000,000,000,000,000,000) Joules of heat energy every second each. This is 6.4 x 1019 WATTS of power – enough to light up the United States for 55 MILLENIUM. In short, they would burst into flames and vaporize into plasma, the 4th State of Matter, instantaneously, exposing the reindeer behind them and creating a deafening sonic boom in their wake which would pulverize the remaining reindeer if they would, indeed, still be there. The entire reindeer team would be vaporized within 0.000 426 seconds, or right about the time Santa reaches the 2nd house of the trip. Not that this matters however, since Santa as a result of the tremendous acceleration from rest to 2,300 MILES PER SECOND in 1/3000th of a second would subject him to a force = 1.1 BILLION times the pull of gravity here on earth. A 250 pound Santa, a conservative estimate, would be pinned to the back of the sleigh by 275,000,000,000 POUNDS of force, instantly crushing his bones and organs and reducing him to a quivering blob of pink goo.

5. Therefore, if Santa ever existed, he doesn't now.

6. But, we all know that Santa DOES EXIST and survives very well, thank you, due to his special powers inherited from his home planet of Krypton.

rocket powered skateboard

You may have seen an earlier post with a video showing the methanol bomb.

This is what happens when you strap it to a skateboard.

dioxin poisoning

The two photos here were taken only a couple of months apart in 2004.

The man is Victor Yushchenko, a candidate in the Ukranian general election of 2004. The campaign was very bitter and often violent, and Yushchenko became seriously ill in early September 2004. He was flown to a specialist clinic in Vienna and treated for a series of acute internal medical problems, claiming to have been poisoned by government agents.

The real cause of his problem was only discovered after a Dutch toxicologist recognized the symptoms of chloracne (characterised by the pockmarked and bloated nature of his face) while viewing television news coverage of his condition. On December 11, Austrian doctors confirmed that Yushchenko had been poisoned with TCDD dioxin, and had the second highest dioxin level ever recorded in a human.

Dioxins are produced in small concentrations when organic material is burned in the presence of chlorine, whether the chlorine is present as chloride ions or as organochlorine compounds, so they are widely produced in many industrial contexts, but the main problem with them is bioaccumulation in the food chain. The sort of doses found in Yushchenko would have been highly toxic and most likely carcinogenic. Dioxin is widely regarded as the world's most deadly man made chemical (just ahead of sarin) based on LD₅₀ figures(lethal dose 50% - the amount of the chemical needed to account for the death of 50% of a tested population).

Despite this major setback to his health, his popularity did not wane, and on January 23, 2005 Yushchenko was inaugurated as the President of Ukraine.

However his bad luck didn't end there. He was struck by a lightening bolt later that year whilst climbing the Ukraine's highest mountain, but again he survived.

flame tests

What happens when you take compounds of strontium, copper and calcium, dissolve them in ethanol and then spray the resulting solutions onto a bunsen flame? Well you get some distinctively coloured flames (crimson red, green and orange), then if you're not careful, you set fire to the desk.

Different metals and metal compounds often give uniquely coloured flames when burned, based on each element's characteristic emission spectrum. For this reason they are commonly used in fireworks to get a variety of different colours during displays.

ammonium dichromate volcano

Ammonium dichromate, (NH₄)₂Cr₂O₇, is often known as Vesuvian Fire, for reasons you can see from the video below. It has been used in pyrotechnics and in the early days of photography. The volcano demonstration involves igniting a pile of the salt, which initiates the following conversion:

(NH₄)₂Cr₂O₇(s) → Cr₂O₃(s) + N₂(g) + 4H₂O(g)

This demonstration finds only limited use because the chromium(III) oxide ash produced by this reaction is toxic, possibly carcinogenic. This is also the reason I get the technicians to clean it up.

liquid oxygen

Strangely, liquid oxygen (LOX) is pale blue in colour and is paramagnetic.

Paramagnetic materials are attracted to magnetic fields (like the poles of a magnet) but unlike ferromagnets they do not retain any magnetization in the absence of an externally applied magnetic field (so don't expect liquid oxygen to attract a piece of steel).

diffusion

Ghostly apparitions, or simply blue ink diffusing into water. Ooohh, ghosts. Scary.

Mpemba effect

Contrary to rational common sense and most of the laws of thermodynamics, hot water will freeze more quickly than cold water.

It's called the Mpemba effect.

For an explanation, have a look here.

why water freezes faster after heating

salt and pepper

This image of a whole peppercorn with a grain of sea salt offers a close-up glimpse of the structure of simple everyday products that we use on our food. Mind you, that's it for me and pepper. No more of that veiny rascal on my cheese sandwiches.

methanol bomb

Methanol is a volatile liquid which will easily vaporise when shaken in a large water cooler, since the relatively weak hydrogen bonds holding the methanol molecules together are fairly easily overcome at room temperature. Being an alcohol, it's also very flammable.

water balloons

Once the balloon has been pierced, the hydrogen bonding between H₂O molecules holds the water together for long enough to retain the balloon shape, before gravity steps in.



If you like this, have a look at some NASA astronauts mucking about in zero gravity conditions with water balloons

NASA water balloons

ban DHMO

The following extract is from "Ban Dihydrogen Monoxide" by the Coalition to Ban DHMO © 1988. Nothing has yet been done solve this worldwide problem. Ask your Chemistry teacher to let you sign the petition if you are still worried after reading this, or visit DHMO.org to find out the truth about Dihydrogen Monoxide. Please take the time to visit the site now, or in the near future. You'll be glad you did.

BAN DIHYDROGEN MONOXIDE - THE INVISIBLE KILLER

Dihydrogen monoxide is colourless, odourless, tasteless, and kills uncounted thousands of people every year.

What are the dangers of Dihydrogen Monoxide?

Most of these deaths are caused by accidental inhalation of DHMO, but the dangers of dihydrogen monoxide do not end there. Prolonged exposure to its solid form causes severe tissue damage. Symptoms of DHMO ingestion can include excessive sweating and urination, and possibly a bloated feeling, nausea, vomiting and body electrolyte imbalance. For those who have become dependent, DHMO withdrawal means certain death.

Dihydrogen Monoxide Facts

Dihydrogen monoxide:
-is also known as hydric acid, and is the major component of acid rain.
-contributes to the Greenhouse Effect.
-may cause severe burns.
-contributes to the erosion of our natural landscape.
-accelerates corrosion and rusting of many metals.
-may cause electrical failures and decreased effectiveness of automobile brakes.
-has been found in excised tumors of terminal cancer patients.

Contamination is reaching epidemic proportions

Quantities of dihydrogen monoxide have been found in almost every stream, lake, and reservoir in America today. But the pollution is global, and the contaminant has even been found in Antarctic ice. In the midwest alone DHMO has caused millions of dollars of property damage.

Dihydrogen Monoxide Uses

Despite the danger, dihydrogen monoxide is often used:
-as an industrial solvent and coolant.
-in nuclear power plants.
-in the production of styrofoam.
-as a fire retardant.
-in many forms of cruel animal research.
-in the distribution of pesticides. Even after washing, produce remains contaminated by this chemical.
-as an additive in certain junk-foods and other food products.

Stop the horror - Ban Dihydrogen Monoxide

Companies dump waste DHMO into rivers and the ocean, and nothing can be done to stop them because this practice is still legal. The impact on wildlife is extreme, and we cannot afford to ignore it any longer!

The American government has refused to ban the production, distribution, or use of this damaging chemical due to its importance to the economic health of this nation. In fact, the navy and other military organizations are conducting experiments with DHMO, and designing multi-billion dollar devices to control and utilize it during warfare situations. Hundreds of military research facilities receive tons of it through a highly sophisticated underground distribution network. Many store large quantities for later use.

It's not too late

Act NOW to prevent further contamination. Find out more about this dangerous chemical. What you don't know CAN hurt you and others throughout the world.

university interview technique

One of our Chemistry students was interviewed at Oxford last year. The Professor interviewing him casually leaned back in his chair, took a sip of tea and then asked him how he would go about calculating how many molecules of liquid there were in his cup.

Now I like to think I would have been able to answer that, but pressure in interview situations does funny things to people. (As it happens he gave a text book answer and got his place on the back of straight A grades).

Another variation on this is to be asked to estimate how many molecules of air there are in the room.

It struck me that if you are going for interview at a prestigious university, or for a course that requires near faultless grades like medicine, then it might be an idea to share any interview experiences.

Leave any details, challenging questions or even any general tales of woe resulting from feeble interview technique in the hope of serving the greater good, by commenting on this post.

alkali metals and water

By the time you reach year 9 you'll have probably seen the group 1 metals lithium, sodium and potassium reacting in water. We can't get rubidium and caesium in school for obvious reasons....

aluminium and bromine

The reaction of aluminium with bromine. Who would have thought that aluminium was so reactive anyway? We wrap our food in it, don't we?

Being protected by an air tight, water tight layer of aluminium oxide on its surface, it is perfectly safe to use as cooking foil. However, bromine is a bit frisky, and once it strips off this thin oxide layer to reveal the reactive aluminium metal beneath, the resulting reaction is highly exothermic.