Sunday, 26 February 2012

By on February 26th, 2012 in chemistry, science kits

09:43 – Barbara just gave me a haircut and is vacuuming now. Today we’ll pack the next-to-last group of chemicals for the biology kits: Barfoed’s reagent, Benedict’s reagent (qualitative), bromothymol blue, fertilizer concentrate B, glycerol, neomycin sulfate solution, Seliwanoff’s reagent A, sodium borate, and turmeric reagent.

As I was making up the Benedict’s reagent yesterday, I thought what a great demonstration it’d be for kids. It’s made up as two solutions that are subsequently mixed with constant stirring. The first solution is sodium carbonate and sodium citrate, which is colorless and water-like. I made up 1.7 liters of that. The second solution is copper sulfate in about 200 mL of water. It’s a beautiful blue color, about the same as Crest Pro Health mouthwash. As I poured the second solution into the first, I thought about having kids watch this part. They’d all assume, naturally enough, that the 200 mL of medium blue solution would be diluted by the 1700 mL of water-like solution to yield a much paler blue solution. In fact, the opposite occurs. The more of the copper sulfate solution you add, the deeper the blue color becomes, until the final 1900 mL of solution is a much, much deeper blue than the original copper sulfate solution.

As to why, most people who know a bit about chemistry think copper(II) ions are blue, but in fact they’re colorless. It’s hydrated copper(II) ions that are blue, because they form an intensely blue coordination complex with water molecules. That’s why copper(II) sulfate pentahydrate crystals are blue, while anhydrous copper(II) sulfate is colorless.

Nearly all copper coordination complexes are blue or green of some sort, but the exact color and intensity depends on the ligand. With water as the ligand, one sees the familiar blue of copper(II) sulfate. With citrate as the ligand, the color shifts to a shorter blue wavelength, and the color becomes much, much more intense.


13 Comments and discussion on "Sunday, 26 February 2012"

  1. Rod Schaffter says:

    Hi Bob,

    Cyan ink-jet printer ink owes its colour to substituted copper phthalocyanine…

    Cheers,

    Rod Schaffter

  2. Chuck Waggoner says:

    Hmm. Somebody just passed this to me.

    http://bits.blogs.nytimes.com/2011/12/20/seagate-wd-storage-warranty/

    It is not new — came into effect at the first of the year, but both Seagate and WD have SUBSTANTIALLY reduced hard drive warranties, in some cases by as much as 4 years. Article speculates that parts for warranty repair were destroyed in the Thailand floods, and there just is no way to fix the number of broken ones being returned without affecting share price, and — of course, — maintaining the CEO’s stock options come before maintaining your hard drive purchase.

    Something is definitely going terribly wrong here. Hard drive prices have skyrocketed, while at the same time, warranties are being stripped to next to nothing. It is not the purchaser’s problem that these companies decided to locate in Thailand. Take the hit for that, and stop gouging the consumer!

    And I may be wrong about this, because it changed while I was in Germany, but my understanding was that Congress legislated that the minimum warranty period in the US for manufactured products sold here is now 2 years — mandated by law. We recently had a piece of radio station equipment made in England, but sold in America, fail. In England, it is warranted only for 1 year, but we were at 18 months. The US distributor told us that, indeed, we were covered. They sent us a new one, which we swapped for the broken one. I don’t see how Seagate can warrant for only 1 year.

  3. OFD says:

    Hitachi makes hard drives, too; are their facilities in Thailand/flood territory also? I could look it up but Mrs. OFD is staying at her mom’s place tonight on the way back from a snowy return trip from Montreal so I get another night of violence and mayhem on the telly. Who else makes hard drives now, I forget…

    I agree with Chuck; this blows.

  4. OFD says:

    Oh, and in other nooz, before I forget, during our phone call a few minutes ago Mrs. OFD informed me that our daughter’s German fraulein friend was very impressed with me and my scholarly personality, and having just learned on their way up that this is a big firearms and explosives zone here, she was fascinated and wishes to converse with me again soonest regarding Americans and firearms, etc. As they in Germany have no clue, apparently.

    Thoughts, Chuck?

  5. Don Armstrong says:

    OFD, give her the talk on US history, founding fathers, Federalist and anti-federalist papers, and the 2nd Amendment.

    Fact is, while firearms are a good thing, the USA is way at one end of an extreme about them. There are other ways which work, but there’s no way you could impose those other ways on the USA without destroying it. Conversely, I guess, you couldn’t introduce USA ways into some of those other cultures without destroying them. Different strokes.

    The USA was founded by, and on, and maintained by, the premise of firearm freedom and an armed populace. Firearms, and firearm freedom, are laced all through your society, and removing them would destroy your civilisation – look at the cities of New York and Chicago as examples.

  6. Miles_Teg says:

    OFD wrote:

    “Oh, and in other nooz, before I forget, during our phone call a few minutes ago Mrs. OFD informed me that our daughter’s German fraulein friend was very impressed with me and my scholarly personality…”

    Tell her that you know a handsome young (or, at least, younger) guy in Australia who isn’t married and likes Germans and Germany. And I’m even more scholarly… 🙂

  7. Don Armstrong says:

    Hell, she’s probably the daughter, or at least knows the daughter, of the neighbour I should have married. There are so very many girls I should have married, and only about two I shouldn’t have – one I did, and one my brother did. Little brother, on the other hand, went halfway around the world to find a pure gem – from India, mark you, Jim lad, but from about the most remote state you can get – Mizoram, tucked up against the Himalayas, Bangla Desh, and Burma Myanmar.

    Still, Greg has some rationale in his come-on-line post – there are still a lot of good guys in Australia. She could come here and meet Mr Good Enough pretty easily. Provided she gets out of the cities, she might even find Mr Right. Note that Greg is in one of the cities, and I ain’t.

  8. OFD says:

    I will take you Oz fellows’ requests under careful advisement. And yes, I realize the special circumstances in regard to firearms in this country, but am still dismayed by what has happened in the UK and the former Commonwealth nations.

    The young woman in question hopes to spend this coming summer in Boston, so maybe a little tour of the road between Lexington and Concord back to Boston where the local militia wrought havoc on the lobsterbacks from behind stone walls and woods still extant. And Watertown, where some old veteran of Queen Anne’s War came out and accosted the Brits and they shot and bayoneted him repeatedly until he finally succumbed. A salutary moral lesson for today’s old vets, perhaps…

  9. BGrigg says:

    I found staying in Boston was a great lesson on history. There is something about walking the same streets that makes it real, instead of just a story in a book. I’d love a return trip one day.

  10. Chuck Waggoner says:

    Of the 9 places I have lived in the US, Boston was my favorite — by far.

  11. Chuck Waggoner says:

    …and wishes to converse with me again soonest regarding Americans and firearms, etc. As they in Germany have no clue, apparently.

    Thoughts, Chuck?

    I think she likes you. Germans definitely know far more about the US than we know about them. Her interest sounds a little devious.

    But maybe they don’t really know things such as how we treat firearms and powder kegs. Don is right — we in the US are at one extreme. One thing I can tell you is that Europe is tired of war. They have bred it out of their lives, by limiting firearms in civilian hands, reducing military to levels that clearly cannot deal with uprisings, should one nation go megalomanic on another, and by being reluctant to talk about it. I really only know the story from my family’s point of view, because no one else volunteered anything of significance, and I was not going to be an ugly American and insist on information. But there are 3 branches of the family with men old enough to talk about the war, and all were in agreement.

    My WWI veteran grandfather never spoke about The Great War. Never; not one word. He would talk about France and the places he was stationed and visited, and the food, and some funny stories about how he learned French, but zero, zip, nada about the war. I learned from my Belgian grandmother (working in a gas mask factory in France when she met my grandfather) and from my mom, that his main job was preparing and installing wooden propellers on the biplanes mostly used in that war, and that a lot (maybe most) of the fly-boys he worked with, died.

    I am not quite sure why my grandfather — or the Germans — were/are reluctant to talk about the war, but the thing I got common agreement on in Germany, from all those who served in WWII (and that was every man who was over 75 while I was there, as kids were regularly drafted as young as 15, definitely by 17) is that control of communication by the Nazis (or preventing it altogether) was what led the country awry. The general public did not know what Hitler was up to. He said one thing, and did another. Soldiers were prevented from seeing family, so no one knew what those soldiers were doing. My daughter in-law’s grandfather did not see his family at all for 8 years from the age of 17 when he was drafted — 6 years in the military, and 2 years after the war as a POW “slave” in France. And by the time people generally knew for sure that things were not as Hitler said, all they could do was pray they would be defeated by the US and the Allies (and not by Russia). And that is what nearly everyone I met who was old enough and would talk about it, said they did — prayed for their own country’s defeat.

    Can you imagine that happening in the US? It was the only choice for the Germany population at large. No wonder they have not wanted to talk much about it, and have been so silent, up until now. Kids today don’t know much about it, because today’s teens don’t have family members still alive who were involved in the war. Thus, they have no remembrance of it, no shame about it, and want to get on with life in the modern era. Filmmakers are just now willing to explore both the division of Germany (“Sundgauer Straße” and “Goodbye Lenin”) and the war itself (“Der Untergang”).

    But I suspect that your friend has not gotten an education about the what and why every man, woman, child, and dog has a gun in Vermont, while hardly anyone in Germany does, unless they are a bonafide artillery or hunting enthusiast. Even then, they have to demonstrate proficiency before they can buy bullets.

    I did once see a guy firing a revolver in the air downtown near the Brandenburg Gate on Silvester (New Year’s Eve). That was pretty scary, because he was quite obviously drunk.

  12. OFD says:

    I would have gone up to the guy at the Brandenburg just to see what revolver he was firing, coulda been a valuable rarity, or maybe just the one that Goering whipped out every time someone said the word “kultur.”

    My grandfather vet of the Great War said doodly-squat about that war, and ditto my other grandfather who did three years in North Africa against the Desert Fox. My dad was in the Coasties in the North Atlantic against der unterseebooten and had jackshit to say about that; his only stories were from Shore Patrol duty in Baltimore and Manhattan beating on drunken sailors and marines. Late uncle from the Navy and ‘Nam also had jackshit to say about his destroyer duty and we didn’t know until after he was dead that he had a Bronze Star.

    I, on the other hand, feel free to wax at length sometimes about my time with Uncle on his plantations in the U.S. and southeast Asia, but mostly the funny stories. I was advised during substance abuse treatment at the VA hospital a couple of years ago to get the bad shit off my chest, preferably with other combat vets. This was extremely difficult to do, but most of it got done, and in return I got to hear some amazingly frightful shit from other guys, esp. the grunts and spec ops people. I suspect, but I could be dead wrong, that keeping it bottled up for another sixty or seventy years after the events is not healthy, and those other vets in my family got old and sick and died, but maybe they wouldn’t have checked out as early or been as surly and taciturn a lot of the time, and mean, actually, some of the time. WWI grandpa dead of cancer; WWI grandpa checked out with emphysema; dad with early-onset Alzheimer’s; and my Navy uncle spent his last few years drinking and smoking himself to death at 63. They have his Bronze Star plaque up on the wall at the New Bedford, MA Legion post where he hung out.

    I checked out Legion and VFW posts off and on after I got back, and even fairly recently, but they are mostly carbon copies of all those dreary NCO clubs from a million years ago where guys just sit at the bar and drink themselves into a stupor while watching whatever shit is on the tube or listening to whatever shit on the jukebox. And smoking ciggies. Fuck that. But I will reach out and try to help other fucked-up vets when I run into them, or for that matter, anyone who needs a hand or someone to listen.

    By the way, not every dog has a gun up here, Chuck.

  13. BGrigg says:

    Taking guns from the civilians just makes it easy for dictators to step up. Who will argue once the citizen’s are disarmed? Those who beat their swords into plowshares, plow for those who don’t.

    I have heard plenty of stories from vets, and from all sides. War is offensive, and dirty, and dangerous, and oftentimes far too necessary, to leave entirely in our governments hands.

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