Saturday, June 28, 2008

y=mx+b is for losers

Everyone who has mowed a lawn or watched professional baseball is familiar with the patterns a lawnmower makes as it cuts the lawn. Here is one example of what I am talking about:

Or here is an example from Minute Maid park in Houston:

The easiest pattern is a linear one, but this is boring. To prove how much of a nerd I really am, I decided to forgo the y=mx+b motif and employ a non-linear function. This week I mowed my lawn in a sin(x) manner. See:

OK, the picture isn't great and I couldn't fit my whole backyard into one shot. I am also too lazy tonight to screw around with Photoshop and merge them together, but you get the idea. The bucket was meant to be a point of reference. It looks better in real life, though one could easily tell I drew this with a lawnmower. It isn't a perfect sine wave.

I was originally going to do ln(x), but I'd still be mowing. *rim shot* (Get it? If not see: [1])

Next week, maybe a zig zag. First I have to figure out the function for a zig zag. Or I could do f(x)=|sin(x)|. hmmmmm, so many possibilities, so little lawn.

[1] Think asymptote.

Friday, June 27, 2008

hop bags

I usually use a hop bag when I make beer. A hop bag is a nylon bag that keeps the hops contained and easily removed from the wort before fermentation. This helps keep the beer a bit cleaner. In addition off flavors can be leached from the hop residue as it sits on the bottom of the fermenter. Removing the hop residue before fermentation helps prevent this.

The main problem with using a hop bag is getting hops into the bag while it is in the kettle.[1] The boiling wort (3 gallons of it) is hot. It's boiling. Boiling water is hot. The bag is full of liquid and cannot easily be removed from the boiling wort. Opening the bag is tricky because the wort is hot (remember).

So, I came up with my own solution: a funnel. I stick a large funnel into the opening of the bag and slowly add the hop pellets. The pellets must be added slowly so they don't plug the funnel. This method also only works for pellets. On occasion, I have hydrated the pellets in water and poured the slurry through the funnel. That works too, but is slower.

Here's a picture.

[1] Brief hop background: There are two main uses of hops: bittering and aroma. For bittering to occur, the hops must be boiled for an hour during which chemical isomerization occurs. For aroma, the hops are typically added during the last 15 minutes of a 60 minute boil.

Wednesday, June 25, 2008

Time for brewing

Lately, the sporadic posts on this blog have been mostly about chemistry. I have seriously neglected posting anything about beer and brewing. How sad.

I plan on brewing tomorrow (I hope). I'm going to make what I call a summer ale. Here is my planned recipe:

Partial mash:
2 3.5 lb pale malt
0.5 lb honey malt
0.5 lb carapils

3 lbs light dry malt extract (late addition)

Columbus- bittering
Willamette- aroma and flavor

I'm shooting for something lighter in color. The hops are from what I have on hand. I think the Columbus will be nice for bittering. At 14% AA,it won't take much to bitter the beer. The Willamette should provide a nice herbal, earthy flavor that will taste good when I am digging in my garden[1].

Any thoughts?

[1] or trying to kill that stupid rabbit that's decimated my garden.

Tuesday, June 24, 2008

Moving pictures of Thermite

Finally, here it is: Thermite.

At about 2:00 I almost die. Well, OK, not really, but I did almost get a lot of liquid iron on my legs.

We tried to melt a tower of Al cans below the reaction, but it just got knocked over. I will need to support it next time.

Friday, June 20, 2008

Thermite video coming soon

By popular demand of one influential commenter, I videotaped a thermite reaction that I recently performed. I am currently on vacation and am away from my videotape. When I am back[1], I will be posting this video on the good ol' world wide web.

Stay tuned.

[1] and when I figure out all of the computer manipulations necessary to get a video onto U-Tube[2]

[2] I know, it's "YouTube" but when I hear "YouTube" I just think of a piece of glassware used for things like manometers and dialysis experiments.

Friday, June 13, 2008

Thermite pictures

Here are some pictures of my recent thermite demo. This one was 1.5 kg iron (III) oxide and 500 g aluminum powder. It was ignited by adding some gummi bears to a puddle of molten potassium chlorate. The pile of potassium chlorate on top of the thermite was melted using a propane torch.

Notice the doomed aluminum cans and the gummi bear below the flower pot.


The stream of molten iron.

The aftermath.


Science Camp 2008: Day 4

Science Camp 2008 is done. What a week.

Today, we did some food chemistry. We tested the vitamin C content in various citrus fruits. First, the campers added a known ascorbic acid solution to some 2,6-dichlorophenolindophenol. The loss of color indicated the endpoint. Then they squeezed the juice from a lime, lemon, orange, and grapefruit and tested the juice. From our most crude experiment, we found that oranges have the highest concentration of vitamin C followed by lemon, lime and then grapefruit. This is probably not a reliable result, but it was a result.

The demo today was gummi bears in molten potassium chlorate (KClO3) and thermite.

The thermite reaction is great. It is a mix of 3 parts iron (III) oxide and 1 part aluminum powder. This is placed in a clay flower pot and ignited. The ignition is difficult. There are a few traditional methods. These include Mg fuse or KMnO4 and glycerol, but both are unreliable. I have adopted a much more reliable method. Since I typically do the gummi bear in molten KClO3 at the same time as the thermite (since both require a trip to the campus fire pit) I once wondered if the gummi reaction could ignite thermite. Yes it can.

I place the thermite mixture in a clay flower pot and make a depression in the mixture. I place a few grams of KClO3 and melt it with a propane torch. When is it mostly melted, I add the gummi bears. They react and then thermite becomes ignited. So far, I'm 4 for 4 using this method.

Hopefully, pictures will appear soon.

Wednesday, June 11, 2008

Science Camp 2008: Day 3

Day three was all about biopolymers. We extracted and precipitated DNA and messed with some starch based non-newtonian fluid.

First we put our DNA in a bottle. The campers swished about 10 mL of water in their mouths to extract cheek cells. These were added to some sodium lauryl sulfate solution to break up the cells. Then some EDTA was added to stop DNA-degrading enzymes. To precipitate the DNA, 95% ethanol was layered on the aqueous layer. This usually, but not always, created a few opaque strands of DNA. If they were careful, they could remove the DNA and put it in a vial.

This was fun, but it didn't work very well. Not every student was successful, but the ones that got DNA were pretty impressed.

Next, we made a royal mess playing with starch and water. This is a cheap and fun way to entertain a kid for minutes. Mixing starch and water in the right proportion creates a non-newtonian fluid. This fluid acts as a liquid when not under stress but behaves as a solid when under stress. A sharp finger poke will reveal its solid nature and a gentle finger poke will reveal its liquid nature.

The demo today was liquid nitrogen ice cream. I made a big batch;
1 quart heavy cream
1 quart half and half
2 cups sugar
a dash vanilla
Stir to dissolve the sugar.
Add liquid N2 slowly to freeze.


Tuesday, June 10, 2008

Science Camp 2008: Day 2

Today was polymer day in Science Camp.

We talked about what polymers are. We spent a fair amount of time talking about plastics.

Try this exercise. Look around you. Any plastics around you? Yeah, I thought so. Plastics define our modern society. Plastics make our modern way of life possible. Identify a few things that contain plastic. If plastics did not exist, what would those items be made of? Or, could they exist at all?

Think of music. Only in recent years has it become possible to store music without some sort of media. CD? Plastic. Compact cassette tape? Plastic. Records? Plastic. etc...

OK, so the point was to illustrate the importance of polymers in modern society

Then we headed off to lab.

In lab we made plexiglass (polymethyl methacrylate). In a doomed glass test tube, about 2 mL of methyl methacrylate is mixed with 6-8 drops of tert butylperoxybenzoate. The tube is stoppered and placed in a 55° C oven overnight. Once polymerization occurs, it's smashy smashy on the test tube to get the bullet-shaped plexiglass out.

Next, we made some nylon by layering a cyclohexane solution of adipoyl chloride on top of an aqueous solution of hexamethylenediamine. With a hooked wire, the nylon is pulled from the solution in a long strand. The strand is washed and dried.

Finally, the classic Elmer's glue, water and borax glop. Since the first two reactions require very careful lab technique due to the potentially dangerous nature of the reactants, it is nice to do something the students can literally get their hands on.

To end the day, we played a round of LMNTO. The winner won a 250 mL beaker (never used).

Tomorrow, we put their DNA (biopolymer) into a vial.

Monday, June 9, 2008

Science Camp 2008: Day 1

Science Camp Day one is in the books. I am beat. Every year I do this I am in awe of teachers that do this for a living. It take a lot of effort to keep 5-8th focused.

Today (in Chemistry) we started with some food chemistry. We did the classic peanut burning lab.

After ensuring no one was allergic to peanuts, we measure the caloric content in peanuts. A unfolded paper clip is stuck into a large cork. The other end is used to impale a peanut. The peanut is ignited using a bunsen burner. The burning peanut is placed under an 8 oz pop can filled with ice until the peanut stops burning. The amount of ice that melts is used to determined how many calories of heat the burning peanut gave off. I help them with the calculations and then we discuss the experiment design and how it could be improved.

During this discussion, I try to explain the difference between a calorie and a Calorie (this has always annoyed me). One food Calorie (capital 'C') is the same as one kilocalorie (little 'c'). So, 1 Calorie = 1000 calories. That is so annoying.

After doing the peanut, we repeat using Cheetos. Let me tell you, Cheetos burn very well. The data is not as good because the large flame makes "catching" the heat difficult since much of the flame goes around the can. But, the students love to see the big fire.

When all was said and done, the values we measured were pretty close to the package values, but typically 10-15% low. This makes sense, since there are significant flaws in the experimental design. However, that is also the point. I want the campers to identify the flaws.

The demo I did today was the "methanol cannon." About 10 mL of Methanol is placed in a plastic bottle (any size up to 20 L). The bottle is agitated. A match is added to the neck of the bottle and the methanol vapors ignite. This makes an impressive fire ball in the container. An attempt to repeat the demo fails and a discussion on the role of oxygen in combustion ensues. As an added twist adding boric acid makes the flame green. For the best results, I use a 20 L plastic water bottle. In small rooms I have blown ceiling tiles out of place.


Science Camp 2008

Today is the first day of Science Camp. I and some colleagues will be hosting about 25 junior high students for a week of sciencey fun and learning.

I chronicled what I did last year. It was fun, but a ton of work.

This year my two main topics are going to be polymers and food chemistry. I'll keep you posted and maybe post some pictures.

Wednesday, June 4, 2008

Sorry for the silence

I just returned from a "wonderful" "vacation." By "wonderful" I mean by the end of the trip my wife and two of my children were puking, and by "vacation" I mean I worked on work-related matters all week. Damn you Al Gore and your accursed internet!!!!!

Oh well, I'm home and able to catch up on the world. All I can say is, "Hillary, the Egoexpress to Egoville left 4 months ago. Time to go home."

OK, sorry for waxing political.

Anyways, I'm back and ready to do work.

Science Camp 2008 is coming. Get ready for updates.
Beer WILL be brewed soon. Prepare yourself.