Dudney,+Sarah

Coins and Chemistry August 30, 2010 I found this article quite interesting; alot of the information in the article was new to me. For example: you could (accidentally) eat the old pennies since they were made out of 95% copper and 5% zinc. When the pennies underwent their makeover in 1982, their makeup was changed to 97.5% zinc and only 2.5% copper. Now you cannot (accidentally) eat the pennies minted after 1982 because the larger amount of zinc in the pennies interacts with they hydrochloric acid in your stomach. I also found the Loonie Toonie part of the article neat. When heated with a Bunsen burner and then submersed quickly in cold water, the Canadian two dollar coin (which is composed of a mostly nickle outer ring and a copper alloy inner disk) can become separated. How does it do this? Copper's rate of expansion is faster than that of the nickle outer ring. Therefore, when it is heated up it expands faster, and when it is cooled down, it condenses faster, making it easy to pop out. Just so you know, the Canadian Government quickly passed a law saying that you could not intentionally separate the coin. Why do they have to ruin all the fun? :)

Sarah, Well written and funny too! 5 stars! MW

Redefining The Kilogram September 2, 2010 Before reading this article, I had never really thought about where our measurement standards came from. I found it interesting to read that the kilogram is the only SI base unit that is still defined as physical object. Why haven't they changed this sooner? Having a physical SI standard somewhat risky considering that it can be easily destroyed (earthquake, fire, etc), whereas an unvarying physical property of nature does not have that risk of destruction. Also in the article I found it the part about how they are going to redefine the kilogram complex. How do people come up with things like Planick's Constant or Avogadro's Constant? My MVP of the article was that the 'redefining of the kilogram' only affects a minute amount of people, mainly metrologists. Now we can all sleep easier tonight.

Sarah, Funny! I hope you slept well. :) I suppose there could be a "ripple effect" on all of us if the standard breaks down but it is sort of hard to imagine such a little lost mass could really make much difference. I agree with you on the risky ideas! 5 stars! MW

Crude Oil September 17, 2010 This video combined a lot of the information we have learned about the past few weeks in class, including mixtures, distillation, densities, etc. I found it amazing how many different substances could be separated from crude oil. I have always known that our gasoline and asphalt come from crude oil, but I never knew how that process occurred. The separation process of distillation is now a common practice in the chemical world, and I find it very cool to finally know what is going on in those large refineries. Maybe we could take a field trip? :)

Sarah, I like your idea of a field trip but I don't think there are any refineries around here. (Plus they really smell!) 5 big stars. MW

Motion Detectors September 27, 2010 Motion detectors very cool. I did know a couple things about them before I read the article. First, I knew that they are commonly used in daily life, such as in your house and at stores. The second thing I knew was that bats use a form of motion detecting (echolocation) to find their food. I also knew that a Hertz is a measurement of frequency. There were lots of new things to learn in this article. Some things that I learned was all of the different kinds of motion detectors; I found the echo ones to be the most interesting. The steel ball vs. ping pong ball illusion was helpful with illustrating the point of the 'photoelectric effect.' The coolest thing, though, was when I learned that our eyes are 'photo sensors;' we all have built in motion detectors!

Sarah, I really like your reference to the ping-pong balls vs steel ball(s) Very good! 5 stars! MW

Where Do Chemical Elements Come From? Abstract October 21, 2010 Chemical elements lighter than iron come from reactions in a star's core; elements heavier than iron form in 'rapid' reactions when the star explodes.

Sarah, OK. 5 stars. MW

Sugar an Unusual Explosive December 10, 2010 Ok, call me a nerd, but I really enjoyed reading this article. I found it very interesting that surface area is everything when it comes to reactions; I had never thought about that before. The more surface area, the bigger the reaction. This principle is the reason why the Imperial Sugar Refinery in Port Wentworth, GA exploded: a tiny spark ignited sugar dust which then exploded and shook up more sugar dust which then exploded and so on. Since there is a lot more surface area in a cloud of sugar dust than there is on a pile of sugar, it was easy for the sugar dust to ignite and explode. The idea of surface area in reactions also relates to the experiment that you did in class around halloween time. As a pile on the table, the powder did not burn very well. But, when you blew the powder into a flame there was an explosion (and it was quite enjoyable to watch :). The variable of time on reactions is also very critical to the outcome of a reaction. Time is the reason why the sugar that we eat does not just burst into flames. When we eat sugar, the reaction that releases energy (the production of gas molecules that expand quickly) is very slow. However, when sugar is burnt, like when roasting a marshmallow over a fire, energy is produced almost immediately. Time makes all the difference. It is so neat to see all of the important factors that go into one simple reaction. This world is so wonderfully complex, and we need to use our equally complex brains in order to prevent further accidents like this one from happening.

Sarah, Good thoughts. Yes we need to be careful with dust - it's a wonder no one thought to clean it up ahead of time. 5 stars! MW

Helium Balloon December 21, 2010 I never gave gas much thought before this unit, and this article made many interesting points that helped me learn more about it. The first VIP was how the buoyant force acts on all objects, especially balloons. When we lit the baloon of helium on fire in class a while ago, we had to light it quickly before it got to the celing. The slight temperature difference from the top of the balloon to the bottom meant that there were slightly more molecules pushing up than there were pushing down, causing the balloon to float. The second VIP was the how the buoyant force creates a slight weight change. The force might be weak on heavy objects, but it is still there. For ex, if you weighed 154 pounds, your true weight would be 154.2 pounds because of the buoyant force acting on you. A balloon has a negative weight due to the buoyant force- I wish I did too! The MVP of the article was definitely the last thought- how a balloon of helium will go the opposite direction when you turn sharply. I believe that is because when you turn, the centrifical force pulls the air that direction, and since the air is being pulled that direction, the helium goes the opposite direction because it's lighter? Please correct me if I'm wrong, but however it works, it is very cool. The topic and principles of gasses are very interesting. Maybe someday someone can take the principle of buoyant force and turn it into human flight! I will be the first in line to try it out :)

Sarah, Looks like this article sparked your imagination! I agree with your He balloon in a car assessment. Very well done! 5 stars! MW