- What tasks have you completed recently? I recently finished the blog on the mole. The most difficult part was coming up with a meme that was funny and original. I decided to go with a twist on the Skyrim meme “Arrow to the Knee”.
- What have you learned recently?
I have recently learned that I am on the loading crew for the marching band’s trip to the Zia Marching Band Fiesta tomorrow. This means that I, along with a couple others, will be responsible for loading the bus with the band equipment such as instruments and flags.
- Next I plan on learning the jazz band audition etude, as well as finish the glog due Tuesday. Hopefully I will have time the adequately prepare for the audition as well as produce a high quality glog in the time alotted to me.
I have a confession to make: I didn’t care about moles before this chemistry class. Now, I actually find the units quite interesting.
I sure science teachers will be happy to know of my interest in Avodgadro’s number (6.022 x1023). This arbitrary number is actually the number of atomic mass units (amu) in a gram. This allows elements on the atomic scale to be replicated on our much larger everyday scale. For example, one mole of H20 is equal to about 18 grams. The molecular weight of H20 is about 18 amu. What surprised me about all of this is how useful it is. It has an immediate real world application. Most of science which I tend to learn, while fascinating, doesn’t seem applicable in the near future. I much as I want to manipulate my genetic code, there is a huge gap between the acquired knowledge and my ability to use it (for now). I could use the information about moles to observe reactions in my kitchen (with adult supervision). In my opinion, nothing relating to the mole is common sense. It’s more like advanced algebra. The mole, like algebra, is sometimes confusing at first. But then you realize the usefulness of the tool. You learn the method to the madness. Suddenly, It’s hard to imagine science or math without a now vital tool.
1. Recently I have finished the homework describing basic stoichiometry. The PhET lab was informative and educational.
2. Recently I have learned that it is nearly impossible for a man to pick up a chair with his feet and torso against a wall.
3. Next, I plan on reviewing some homework in math.
Let’s begin with an example:
Suppose I have a glucose molecule. (C6H1206) What percentage of the molecule’s mass is carbon?
The first step is to identify the atomic weights of the various elements in glucose. With the help of a periodic table of elements, we know that carbon‘s atomic weight is roughly 12.011 atomic mass units (amu). Hydrogen‘s atomic weight is roughly 1.008 amu. Oxygen has an atomic weight of 15.999 amu.
The second step is to multiply the element’s atomic weight by the number of atoms in the molecule, and add the new atomic weights together. Let’s take carbon as an example. There are 6 carbon atoms in glucose. Therefore, we multiply 6 by 12.011. We get 72.066 amu. See if you can find the atomic weight of glucose using this strategy.
So you should have gotten about 180.156 amu as the mass for the entire molecule. In order to solve the original question you divide 72.066 (carbon’s mass) by 180.156. The answer is 4/10. Therefore, 40 percent of a glucose molecule’s mass is carbon. We can apply this on a larger scale also. If I had 10 grams of glucose, I could expand 4 grams to be pure carbon.
Using this knowledge, we can predict how matter will change during a chemical reaction. We can also figure out the amount of a substance that will be created during processes such as combustion. This is only the tip of the iceberg. Scientists can deduce more about chemical processes using units such as the mole and employing empirical formulas.
- Over the course of the last week I finished the lengthy nomenclature assignment. The assignment reminded me of the importance of foresight. I didn’t procrastinate and leave the assignment for the last minute, but still I had to sacrifice a couple hours of sleep to finish the worksheet. I managed to get 95% of the assignment done two nights before the due date. The event was another small win in my seemingly eternal battle against procrastination.
- Recently, I stumbled across my dad’s copy of The Economist. Inside of the newspaper was an interesting article about international chess play. Chess has always been a hobby of mine. The article talks about the World Chess Federation, (FIDE) and how it is revamping their system so tournament play is better suited for spectators.
- Next I plan on studying english vocabulary. I have a test sometime next week. Or maybe I’ll watch TV…
1. Recently I have finished numbers 150-190 the nomenclature worksheet.
2. Recently I have learned a little bit of the mole. I have also rediscovered my knowledge of significant figures.
3. Next, I plan on finishing the rest of the nomenclature worksheet.
Imagine you are in Science class. You recently received the results from your last test. You received a (insert grade here). However, you scored incorrectly on a problem because you rounded to the wrong decimal place. After politely arguing with your teaching in an attempt to forage for a couple of points, you concede defeat, and wish your teacher had explained the reason for rounding to a seemingly arbitrary number. Then you come to your senses. It’s not like you’ll ever use this stuff outside of science class, at least, not in the near future. Little did you know how wrong your conjecture was…..
Promptly afterward, you saunter to your english class. Relieved by the change of topic, you quickly compose a short essay on ancient warfare. Worn by your last altercation, you ignore the blatantly obvious fact that the topic was better suited to a world history class. Your late obsession with The Hunger Games left archery as the clear focus. After repeated comments on the accuracy of the ancient bowmen, you nonchalantly search the internet for a synonym for accuracy. After substituting various “accuracies” for “precisions”, your science teacher senses a disturbance in the scientific universe, materializes in your English class, and proceeds to give you a confusing rant on the difference between accuracy and precision. Then your science teacher remarks that there is a method to madness, and you realize that maybe, just maybe, there is order to the universe as we know it.
Despite the seeming irrelevance of the above paragraphs, I feel they emphasize the importance of these concepts in the scientific community. Let’s explain significant digits. No matter what measurement system you use, there will always be inaccuracy. It is an unavoidable part of scientific study. Scientists use significant figures to clarify these innate inaccuracies. The last digit in the number is always an estimate. For example, in the article we were supposed to read prior to the blog, the weight of gold was changed from 196.9~(4) to 196.9~(5) atomic mass units (amu). The last digit is one the scientists are estimating. This attention to detail is crucial to ensure the best results. If the weight of gold was rounded to 197 amu, it may have not affected some calculations, but in today’s world of advanced math and science, that small fraction is crucial.
Accurate and precision, despite their interchangeability in normal use, are different in a scientific context. Accuracy is how close the measurement is to the actual object, while precision is the repetition of the measurement. A common way to clarify this is to imagine accuracy as an array of bullet points fairly close to the center of a target. Precision is a close bunch of points, with no regard to the center of the target. This probably explains your science teacher’s passionate speech regarding the subject. As to how this applies to the article’s measurements, the change it digits would increase the measurements accuracy.
So, that is the big deal about significant digits, accuracy, and precision. They are a fundamental part of science that are necessary to ensure that scientific measurements are consistently reliable.