Friday, 5 September 2014

By on September 5th, 2014 in lab day, science kits

07:55 – We’re all caught up on shipping kits. The only orders outstanding are the ones that came in overnight and this morning, which we’ll ship this afternoon. Meanwhile, I need to make up a bunch of solutions today and get started on bottling them.

One of those solutions is 4 liters of 6M sodium hydroxide, which has gotten me thinking about chemical storage. I’m down to my last three 500 g bottles of sodium hydroxide. When I finish those, I have to open a new container of sodium hydroxide, which in this case is a 10 kilo bucket rather than a 500 g bottle. Right now, that 10 kilo bucket is sitting on the floor because it won’t fit my storage shelves.

When we got started building science kits a few years ago, I put up shelves for chemical storage. Most of them are 4″ (10 cm) wide with vertical separation of 6″ (15 cm). Those worked fine when I was buying chemicals in 25 g, 100 g, and 500 g bottles. They’re not wide enough now that I’m buying a lot of chemicals in 1-kilo, 2- or 2.5-kilo, 5-kilo, and 10-kilo containers. That’s why there are still a couple of cartons of chemicals from Fisher Scientific sitting on the floor where UPS delivered them. I thought about repackaging them into 500 g and one kilo bottles, but that’s just too much work. Instead, I think I’ll remove some of the smaller shelves and replace them with wider shelves with more vertical separation. But that’ll have to wait for things to calm down a bit around here.


11:02 – I’d forgotten how obnoxious lead acetate is. We provide a 0.1 M solution of lead acetate in many of our kits, and I was just making up four liters of the stuff. I weighed out the appropriate mass of reagent-grade lead acetate and added it to distilled water. One might expect a nice, clear water-like solution to result. Instead, one gets a solution that looks like milk, literally.

The problem is that most common lead salts, with the exceptions of the acetate and the nitrate, are extremely insoluble in water. And water exposed to air just loves to suck up carbon dioxide. At room temperature, a liter of water dissolves about 1.6 grams of carbon dioxide. That doesn’t sound like much, but with the molar mass of carbon dioxide about 44 g/mol, that means that plain water exposed to air is actually about 0.036 molar with respect to carbon dioxide. That carbon dioxide reacts with water in a reversible reaction to form carbonic acid, the acid whose salts are carbonates. And lead carbonate is extremely insoluble in water, which is why my solution looks like milk. That 0.036 molar carbonic acid reacts 1:1 with my 0.1 molar lead acetate solution precipitating out nearly a third of the lead ions as insoluble carbonate. What’s worse is that that reaction removes the carbon dioxide from the solution, so it promptly sucks more carbon dioxide out of the air, until all the lead is precipitated and the solution reaches equilibrium with about 1.6 g/L of dissolved carbon dioxide. Basically, my dilute solution of lead acetate eventually turns into a dilute solution of acetic acid with most of the lead precipitated out as lead carbonate.

Fortunately, one can use Le Chatelier’s principle to shift the equilibrium by dissolving the lead acetate in a dilute solution of acetic acid rather than plain water. Although it’s a weak acid in absolute terms, acetic acid is a much stronger acid than carbonic acid. That forces the equilibrium of the reversible carbon dioxide <-> carbonic acid reaction to the left, keeping the dissolved carbon dioxide in the form of the molecular gas rather than the carbonate ion. And the lead acetate remains in solution as lead acetate.

42 Comments and discussion on "Friday, 5 September 2014"

  1. Chad says:

    Here’s a neat article for those of us who used to dial into BBS’s:
    http://arstechnica.com/gadgets/2014/01/modems-warez-and-ansi-art-remembering-bbs-life-at-2400bps/3/

  2. Robert Bruce Thompson says:

    Geez, I remember it at 300 bps, when 1200-bps modems were a thousand bucks.

  3. Robert Bruce Thompson says:

    Heh. I just looked around to see if I still have any of my old modems from back in the days when I ran an 8-line Galacticomm Major BBS. (I still remember how incredulous the woman from the phone company was when I told her I wanted them to install eight more CO lines at our house, in addition to the four we already had.) As it turns out, I don’t have any of the USR modems I used. I still have a couple of external 28.8 PP modems that I used for other purposes.

  4. Miles_Teg says:

    Fortunately, I bypassed the Stone Age. My employer had mainframes, the only computers that mattered back then, linked by dedicated microwave. I got called in to work one Saturday morning in February 1986 because my boss, the usual on call person, was up ’till 0430 dialing in to a bulletin board on his Commodore Amiga 1000. Got five hours overtime at double pay but it wrecked my Saturday.

    IIRC I started out at 33k dial-in in 1997 and within a year or two was at an amazing 56k.

    Nowadays I don’t know how I did without broadband at home and my wireless iPad.

  5. Chad says:

    I bought a modem after I got my first job. It was 1992 and it was an external 2400 made by Intel. Bumped that to a 14.4 a year later. I dialed up all of the local BBS’s, but started gravitating toward the ones that were powered with C-Net (an Amiga-powered BBS server software) as I just liked the feel of them better. Lots of good times. Met several friends I still have to this day. Used to occasionally get together “in real life” for meet-ups to put faces with BBS handles and those would sometimes get a little crazy. I tended to use the more social BBS’s as opposed to the ones that catered to the tech crowd.

    I was pretty into it from 1992 until I joined the USAF in early 1995 and no longer had my parents’ computer to use. I would occasionally dial in from a friend’s computer or from my parents’ computer when I was home on leave, but by about 1996 BBS’s were dying off fast and by the time I bought my own computer in 1998 BBS’s were pretty much dead as everyone had moved on to the Internet.

  6. rick says:

    I got my first 300 baud acoustic modem in about 1979. Used it to dial into the PDP 11/70 running Unix at school. Ran a Fidonet BBS in the mid ’80’s. I have had ISDN, Satellite and various other “high speed” connections. I had a BSDI Unix box co-located at a local ISP for a number of years. I currently have a dedicated CentOS machine hosted at a provider in Connecticut. At home I have a 40 meg down, 20 meg up DSL at home through Centurylink. Both Google and Centurylink are promising gigabit service here. I’ll believe it when it’s installed and I can see the promised speed.

    Rick in Portland

  7. brad says:

    I used some BBS stuff, MUDs, forums, and the like. But spent more time gaming alone or directly with a friend. Don’t I vaguely remember the first modems as 110 baud, putting the headset into a cradle? Then 300/1200/2400/9600/56200

  8. Chad says:

    I see WordPress 4.0 is out now. Going to upgrade?

  9. Robert Bruce Thompson says:

    I upgraded to WP 4.0 last night. Or was it this morning? Things blur together.

  10. Chad says:

    I haven’t used WordPress in quite a while. Do you have to install updates manually, or do they have a one click update from within the admin tools?

  11. Robert Bruce Thompson says:

    Depends on how you’re set up. You can host a site at wordpress.com, in which case they do all the work for you. I use dreamhost.com, which has quite a few “one-click installs” including wordpress. Once it’s installed, you’re notified of available updates for the main program, themes, add-ons, etc. and can choose to update or not. Some of the items offer the option for automatic update. Then there’s the worst of both worlds. Until recently, dreamhost would notify me that a WP update was available, but if they got tired of waiting for me to update manually they’d just auto-update it whether I wanted them to or not. They seem to have stopped doing that a couple months ago, or at least I’ve been notified of updates, chosen not to install them for a week or two, and not had dreamhost install them for me.

  12. Chad says:

    Do you rotate pipes? I read a lot about how smoking a briar pipe too frequently would mess with its moisture content and that plus the heat would make it crack. So, you’re supposed to let it cool down completely between smokes and only smoke it one day a week. So, ideally you’d have 7 pipes in a daily rotation. I seem to remember my father always using the same pipe with almost total disregard to all of those rules, but still, it is a widely publicized method of pipe care. Thoughts?

  13. Robert Bruce Thompson says:

    Oh, I don’t do any formal rotation, but I have half a dozen or more that I smoke regularly.

  14. Lynn McGuire says:

    I heard that Zuckerberg spilled a can of coke in the server room yesterday.

  15. OFD says:

    Was it Coke or Pepsi? Us operator drones back in the day used to call that “Pepsi Syndrome,” after it fried something electronic.

    I had them old dial-up 300-baud modems and used to hit the long-dead Boston Computer Society’s boards; my first PC was a DEC Rainbow, and eventually it just became a dumb terminal so I could log into the systems at work (DEC) and check on stuff.

    Not so bad at the salt mine today; I got some stuff done OK and other stuff failed, about 70-30 in the plus column today, whereas yesterday I batted 100-0 with many more issues, too. We’re gonna help out the gun shop guys with a new Windoze box and fix up their crappy internet for them; they tried to go wireless and it’s sucked rocks; we’ll get them all wired up; they’ve been doing 2,500 AK’s a month, some already assembled and some just getting parkerized or whatever. And I discovered once again that the ATF is still basically in the pencil-and-paper era with logbooks and suchlike.

    Too warm and way too humid here today and next couple of days, they say. We’ll have some more warm weather and then go from 0-90 in the next change, or I should say, 90 to below zero, maybe for most of the wintuh. Gotta assemble firewood racks and order two or three more cords and make sure the oil tank is full and vehicles always have full tanks. Also winter emergency kits for both vehicles.

    GM at work told me today they’re looking to bring on a tech school part-timer to help me out while they post for the full-time crony position I wrote the job description for; it’s in the hands of the HR Geheimpolizei now.

    Now to screw off and lay back the rest of the night; up in the AM to put $ in Princess account so she can buy wicked expensive textbooks; finish paperwork at cah dealuh; dump run; and then into work to do stuff I can’t do during the week, mainly get rid of junk and rubbish and fix up my factory-style office. Got some of that done today, amazingly.

    I’d post a few nooz links here but it’s too depressing; gets worse by the day what our regime is doing and plans to do. If I was even twenty years younger I’d seriously consider moving to Chile, San Marino, or Andorra.

  16. Lynn McGuire says:

    Got a call from Verizon yesterday and my five acre IRA property has made the list of three for them to locate their new cell phone tower. This process started about nine months ago and I thought that it had gone dead. They upped their offer from $500/month to $800/month. I said I would think about it. They will get back to me in a month or so.

    I would really like to have that $800/month for my IRA. That would more than cover my $7K expenses per year for property taxes and mowing.

    The killer is that it will cost them about a million dollars to build the tower with backup power, etc. Their property taxes will be $20K/year alone. I am surprised that they are bargaining so much for the land lease price.

    BTW, the Fort Bend Tollway authority is conducting yet another study putting a toll bridge across the Brazos River from the Fort Bend County tollway in the back of Sienna Plantation subdivision to Thompson’s Landing. When that bridge goes in then the traffic out front here will double or quadruple.

  17. SteveF says:

    Why do they need a bridge over the river? I’d think that there were so many firearms lost in the river that you could just drive over them.

  18. Lynn McGuire says:

    It is a big river. They used to run paddle wheelers up it to Waco until the early 1900s. You could probably throw all the firearms in the USA in it and not even cover the bottom. The distance from the South I-69 bridge in Sugar Land to the Rosharon bridge is about 20 miles. The new toll bridge will split that.

    The real problem is the population of the Houston metropolitan area is growing at four percent per year. All those new folks gotta live somewhere. There was 38,000 new homes built in the Houston area last year and I’ll bet that there will be 50,000 new homes built this year. The demand is probably 70,000 new homes per year though.

    New homes mean new roads. Or is that new roads mean new homes according to the suburban sprawl theory?

  19. pcb_duffer says:

    The first modem I had was 300 baud, part of a dumb terminal for dialing into Ma Tech’s computer systems. Even at that speed it was better than hiking to the computer buildings. My first modem for a PC was 1200 baud, I really wanted 2400 but they were just too expensive. I finally got one, and with some effort could read 2400 baud scrolling; then 14.4 put and end to that. Somewhere in the stack of boxes I think I’ve still got a 56K hardware modem, probably ISA based. I can also remember, in about 1990, visiting a college buddy who was doing post doc research at the Triangle Universities Nuclear Lab, on Duke’s campus. He mentioned some problem they were having with their dial up systems, and I rattled of a Hayes dialing sequence off the top of my head which solved the problem. Suddenly the group of 12 people with PhDs in physics were looking at me as though I was the smart guy in the room. Uh, no.

  20. OFD says:

    “Or is that new roads mean new homes according to the suburban sprawl theory?”

    Whichever. But it appears that you may be one of the first pioneers in the new mega-cities of the few-chuh and living as just one among millions per square mile. Maybe the actual road traffic will slowly fade away in favor of them Jetson-mobile flying cahz, though.

    As for net speed and computers, I guess I’ve seen an increase in speed on both since those early days, but not much over the last few years; we may be a special case living where we do, but geez, I have 16GB of RAM in this box and it ain’t much different opening stuff up from what it was during XP and Win2K days. Our ISP informs us that we’re at the fastest possible speed for residential customers and lately it sucks rocks. I asked about upgrading to a business plan, seeing as how both of us need wicked fast net times, due to our work, and someone was supposed to call but never has. Guess they don’t need the money. And wireless here blows. I’ve got my main machines hardwired; cell phone coverage is ridiculous, both here and at work, but I can go a mile up the road at either site and get five bars on the phones.

    Oh yeah, they gave me a company phone today, an iPhone 5s. No charger so I picked one up at Staples, plus a holder for the vehicle dashboard. And an Apple wireless keyboard to connect to it; I have big fat fingers and can type pretty fast so them little smartypants phone keypads are a PITA.

  21. MrAtoz says:

    Houston, maybe the first PRC, Mr. Lynn.

    BTW, are you reading the sequel Lines of Departure. I started it last night.

  22. Lynn McGuire says:

    Houston, maybe the first PRC, Mr. Lynn.

    Nah. Detroit will be the first PRC.

    BTW, are you reading the sequel Lines of Departure. I started it last night.

    Finished it last night. Here is my review:
    http://www.amazon.com/review/R1RGXIFHGWJ206/

  23. MrAtoz says:

    My daughter (one of the Twins) and I are big Iron Druid and Dresden fans. She loves Monster Hunter, also.

  24. MrAtoz says:

    Mr. Lynn did you ever see the short lived Dresden TV series. Bob The Skull!!

  25. OFD says:

    PRC’s to come, in order:

    1.) Detroit. But I’m betting it will become a rubble-strewn concrete jungle slag heap inhabited by cannibals and revenants, intent on their next BBQ long pig dinner.

    2.) Lost Angels. i.e., lost demons. Well on the way. Habla Espanol, Senor?

    3.) Houston. We have an eyewitness on-site reporting the incoming.

    4.) Babylon-on-the-Hudson. Also well on the way, but also a good chance of it becoming a similar cannibal hellscape, especially if hit again by more “terrorist” attacks and rising sea levels.

    5.) A toss-up between Chicago, New Orleans and Miami, any one of which, or all of which could just easily turn into urban hellscapes beforehand.

    I leave Mordor-on-the-Potomac for last, as it sits on a swamp and will very likely eventually resemble the lost jungle ruins of the Maya and Aztecs, but with the same bloodthirsty denizens there as found back then and in the book “Congo” by Robin Cook.

    No time for science fiction and dystopian epics when we have a real live one unfolding before us. I’m getting ready for Halloween early; “The Book of Enoch,” “Malleus Malificarum,” and “Days of Judgement, Days of Doom,” by the very late Reverend Michael Wigglesworth. Maybe I’ll top it off by some browsing of “Magna Christi Americana,” by the very late Reverend Cotton Mather. Ya just gotta have a regular dose of old-timey New England Puritan mania to remind ya how its strain still surges through Murkan cultural and political bloodstreams. Behind them all, the spectres of Calvin, Luther and Satan.

  26. MrAtoz says:

    PRC’s to come, in order:

    I was running errands and saw no less than 8 new residential developments. I’d nominate Vegas as a PRC, but when the aqua runs out, it’ll just be a ghost town. Viva La Dust Bowl baby! Still looking at WA to retire-retire. Gotta avoid the commies, though.

  27. ech says:

    At my first job, one of my tasks was helping our customers order phone lines to hook modems to. Back then, you could ask for a “data communications line” and they would test the pairs to give you the cleanest one they had. We had all our customers install them (modems rented from the telco) and we had a couple of acoustic couplers that the on-call staff would take home for the week you were on call, along with a TI Silent 700 terminal (built in coupler) and a 24×80 video terminal. Both got a lot of work out, as did my phone credit card. You also were advised to tell the operator that the call was a datacomm call so they didn’t freak out at the modem tones and would drop off as soon as the ringing stopped. We also had a room at work with a couple of VDTs attached to modems, and DEC hardcopy terminal.

    I remember when we upgraded to 1200 bps modems. Much, much better.

  28. Miles_Teg says:

    Boy, Serena plays good tennis but hasn’t been getting enough beauty sleep:

    http://www.abc.net.au/news/2014-09-06/serena-thrashes-makarova-to-advance-to-us-open-final/5724416?section=sport

  29. Lynn McGuire says:

    Mr. Lynn did you ever see the short lived Dresden TV series. Bob The Skull!!

    I lasted about 5 minutes and moved on. Just was not for me.

  30. Lynn McGuire says:

    Ah, the good old silent 700 with the acoustic coupler. Dad got one in 1974? and I would sign into the UCC Univac 1108 and play Lunar Lander for hours using console mode. Dad had a free account on UCC that was only supposed to be for development but we would use it for everything. Including Lunar Lander.

  31. Lynn McGuire says:

    Nice article on Joan Rivers.
    http://blogs.wsj.com/peggynoonan/2014/09/05/joan-rivers-the-entertainer/

    I have to admit, I used to like her on The Tonight Show back in the 70s. And my wife religiously watches Fashion Police and I have watched it with her quite a few times. Crazy stuff.

  32. Miles_Teg says:

    My father smoked a pipe (and cigarettes) back in the Sixties (and before). I never saw more than one and don’t think he rotated them. He went cold turkey in 1965 and within months couldn’t stand to be near smokers.

  33. brad says:

    @Lynn: What’s to think about – take the offer! That’s a fair bit of money for zero effort on your part, plus you’ll have amazing phone reception.

  34. OFD says:

    I saw that same article by Noonan on Rivers; apparently her death is being investigated; stuff like that happens but still weird; she was fine the night before and working and showed no signs of slowing down. Again, another comic who was very funny *sometimes* and not so much at others, and had a passel of torment back in their life somewhere.

    Yeah, Mr. Lynn, I echo brad here; I’d snap that up in a hahtbeat.

    Then I’d move fah, fah away ASAP. Regahdless of phone reception. Let the teeming millions enjoy it.

  35. Lynn McGuire says:

    @Lynn: What’s to think about – take the offer! That’s a fair bit of money for zero effort on your part, plus you’ll have amazing phone reception.

    Sorry for being unclear, I do not have a offer yet. There are three finalists for the cell phone tower location. They will make their decision in a month or ten and get back to me.

    And yes, I would rather have $800/month for a 50 ft by 50 ft space out of my five acres than have nothing.

  36. brad says:

    The Internet gets scary sometimes. Y’all see the kitty-cat picture I have associated with my login. This is one of the few sites where I don’t mind showing my identity – real name, etc. – but the cat is cuter than I am.

    I comment under a pseudonym on a couple of other sites. Suddenly, the cat picture has started appearing on those sites as well – even though I have pretty tight security settings on my browser (no third-party cookies, ghostery turned on, fake user agent string, etc.).

    I’m honestly not quite sure what’s going on; some weekend when I have time, I’ll have to hunt it down. Stupid, that the big companies out there insist on sharing user data, even when it ought to be pretty clear that I don’t want them to…

  37. Don Armstrong says:

    brad says at 6 September 2014 at 05:22

    @Lynn: What’s to think about – take the offer! That’s a fair bit of money for zero effort on your part, plus you’ll have amazing phone reception.

    Yea, verily! I eventually managed to take up our Commonwealth Government rural broadband offer when they eventually got 4G mobile broadband working, and it’s g.o.o.o.d stuff. Fallback to 3G is good, but when it’s running the full-bore 4G (which you can almost always get with an itty-bitty 12″ plug-in aerial)… Oh, my!

  38. OFD says:

    “…Y’all see the kitty-cat picture I have associated with my login.”

    Oh? We can do that? How so? I wouldn’t mind varying a pic from time to time here for my login.

  39. Lynn McGuire says:

    Right now, I have two 12 mbit DSL lines in my office joined together with a peplink 30. I have 100 mbit fiber at the front of my property but AT&T wants $20K to put in a splitter / router. So if the cell phone tower gets installed then they will put in a splitter / router. And I am thinking that I can piggyback my office router on that.

  40. SteveF says:

    I’m sure you can piggyback. For, say, $20K.

  41. Rod Schaffter says:

    Hi Bob,
    When I did Quant lab prep eons ago, we boiled the water briefly to drive off the CO2 when preparing stock solutions…

  42. Robert Bruce Thompson says:

    Yep. Distilled water, brought to a rolling boil for a couple of minutes, and with the salt added while it was still hot to the touch. As you know, most of the CO2 was driven out by bringing the water to a boil, but as it cools it immediately sucks more CO2 out of the air.

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