Friday quiz

[AstralTraveller (David)]

Now let's get this straight. I told the person who knew the answer he was wrong. Then I told someone who didn't know the answer he was right.

The next quiz is: spot the prize goose.

[julianh72 (Julian)]

OK, ice made from heavy water would work, but a MUCH cheaper and easier way is to make ice from a saturated sugar or salt solution. Heavy water will cost you about $1 / mL - if you can find any.

When you dissolve sugar or salt in water, the density increases - the sugar / salt "fits in between" the water molecules, and the volume barely increases. Sugar is easier, because it will freeze in your normal freezer. Saturated salt water freezes at about -21 Celsius, which is a bit beyond the capacity of the average home freezer. If you put less salt in, the freezing point will be higher, but the density will be lower, so it may not sink. Saturated sugar water will still freeze at about -10 Celsius, so you can easily make nice dense sugar-ice cubes in your home freezer.

A neat party trick - make a tray of normal ice cubes and a tray of sugar water ice cubes, and put one of each into the drinks. The plain water cube floats, the sugar water cube sinks, and is perfectly safe to drink as it melts. (Please don't try this with a good single malt scotch though - save it for the soft drinks and cocktails!)

[Baddad (Marty)]

Hi Julian,
I'm afraid I would have to disagree with that method. Its like putting a lead sinker in the ice cube. Its not just water any more.
Heavy water is still 100% water or near enough to it.

Cheers

[Baddad (Marty)]

It worked - you fooled me. I think the 'LOL' threw me. Sorry. Have a cigar!

Thanks David. But I don't smoke.

[AstralTraveller (David)]

Originally Posted by julianh72

OK, ice made from heavy water would work, but a MUCH cheaper and easier way is to make ice from a saturated sugar or salt solution....

When you dissolve sugar or salt in water, the density increases - ....

Originally Posted by Baddad

Hi Julian,
I'm afraid I would have to disagree with that method. Its like putting a lead sinker in the ice cube. Its not just water any more.
Heavy water is still 100% water or near enough to it.

Cheers

Actually both D2O and sugar solution demonstrate something scientific, whereas the sinker is trickery. The D2O is more 'exotic' in that it happens at the atomic level rather than molecular level, is more outside the realm of everyday experience and is certainly more expensive. Also, we all know about sugar solutions (generally we are too familiar with them ) but stable isotopes are something that, even though they are all around us and in us, are still outside most peoples knowledge. [Their use in science is also largely unknown.]

Originally Posted by doppler

"Where to buy is not hard, only $700 per liter"

The kids can look at the picture

That is much cheaper than I would have expected. We pay in that range for ultra-high-purity nitric acid. Even a set of cartridges for water purification - so you can get water with nearly nothing in it - cost us about $2.5-3k a set. I remember being told about some exotic reagent that is $30k per litre but I can't recall what it is.

[ZeroID (Brent)]

Originally Posted by AstralTraveller

.... I remember being told about some exotic reagent that is $30k per litre but I can't recall what it is.

Aqua Regia ? The Acid that chews through glass ... Sulfuric and Nitric Acid mixed...

EDIT: second thoughts ... HydroFlouric Acid ... real nasty stuff ..

[julianh72 (Julian)]

Originally Posted by AstralTraveller

I remember being told about some exotic reagent that is $30k per litre but I can't recall what it is.

Printer ink cartridges cost almost that much!

When you work out the cost per litre it costs more than Chanel No. 5.

[julianh72 (Julian)]

Originally Posted by ZeroID

The Acid that chews through glass ...

I remember my Chemistry teacher back in High School used to tell the joke about the Chemist who spent 20 years searching for the perfect solvent (that would dissolve anything it came into contact with) - and then spent the next 20 years looking for something he could store it in.

[sjastro]

Originally Posted by julianh72

Printer ink cartridges cost almost that much!

When you work out the cost per litre it costs more than Chanel No. 5.

Cheaper than antihydrogen which is going at a cost of US $62.5 trillion dollars per gram.

Steven

[andyc (Andy)]

David's mention of fluorinating reminded me of this entertaining post in a series entitled "Things I won't work with". FOOF is extraordinary and not a little horrifying, and the few experimental scientists who've made it and played with it are surely insane... even in the chemical world

"And he's just getting warmed up, if that's the right phrase to use for something that detonates things at -180C (that's -300 Fahrenheit, if you only have a kitchen thermometer). The great majority of Streng's reactions have surely never been run again. The paper goes on to react FOOF with everything else you wouldn't react it with: ammonia ("vigorous", this at 100K), water ice (explosion, natch), chlorine ("violent explosion", so he added it more slowly the second time)..."

[OzStarGazer]

I remember we had this in school! But only theoretically, maybe because heavy water is so expensive?