Showing posts with label chemistry. Show all posts
Showing posts with label chemistry. Show all posts

Saturday, October 13, 2007

Chemistry Experiment


Chemistry AS403 – Experiment

Chemical reactions proceed at a set rate, but the rate varies depending on many factors. Environmental conditions in particular have a major impact on the rate at which reactions may proceed.

Undertake the following experiment at home to test this principle.

Buy a box of Alka-Seltzer anti-indigestion medication. This product combines acetylsalicylic acid (aspirin), sodium bicarbonate (baking soda) and citric acid.


You will be conducting an experiment with 3 tablets. Place one tablet in a glass of hot (but not boiling) water, another in a glass of ice-cold water, and a third in a glass filled with water that is at room temperature. Measure how long the fizzing continues in each glass after dropping the tablet.

Prior to the experiment, construct hypotheses about (1) the likely outcome and (2) the mechanism by which the fizzing is produced. After gathering data, interpret your results, design any follow-up experiments that might be needed to refine the data, and make a list of factors that might have impacted the accuracy of your experiment.

Feel free to use the left-over Alka-Seltzer to sooth your heartburn....

Fundamentals of Chemistry, Day #1 Lecture Notes


Chemistry AS403 – Lecture 1 Notes: Fundamentals of Chemistry

Okay, let the good times roll. Today we cover the basic tools one needs to start taking a crack at chemistry.

Let’s start with VOCABULARY, some simple definitions that will put all of us on the same page as the game gets underway. In alphabetical order:

  • Accuracy = closeness of a measured value to the true value
  • Atom = the smallest particle of an element (Gr. atomos = “uncut”)
  • Chemistry = a science that investigates the composition of materials and how their properties change by their environment
  • Compound = substance combining fixed proportions of 2 or more elements
  • Density = ratio of an object’s mass to its volume
  • Element = a substance that cannot break into a simpler one
  • Energy = a quality allowing an object to do work. The two main classes:
    • Kinetic = energy in a moving object
    • Potential = stored energy (which can be converted to kinetic type)
  • Heat = energy that is transferred among objects with different temperatures
  • Law = a broad generalization known by experimentation to be true for all people and all times
  • Mass = the quantity (NOT weight!) of a given substance
  • Matter = anything that occupies space and has mass
  • Mixture = material combining variable proportions of 2 or more substances
  • Molecule = Smallest particle of a compound
  • Precision = closeness of repeated measurements to each other
  • Property = characteristics unique to a given substance. Two types are:
    • Chemical = trait that can change as a substance reacts with others
    • Physical = trait that can be observed without changing the substance
  • Specific gravity = ratio of a substance’s density to that of water
  • Temperature = property proportional to the average kinetic energy
  • Theory = a well-tested explanation of a natural phenomenon
  • Weight = the force with which a substance is attracted by gravity

Once we have a common lingo, we need some other COMMON PROCEDURES. Chemists, indeed all scientists, use the following tools each and every day. The “Big Three” pieces in the tool kit are the International System of Units (SI), Significant Figures, and Scientific Notation.

The SI scheme offers standard units of measurement for seven basic quantities. The most common in the chemistry laboratory are for length (meter, m); mass (kilogram, kg); time (second, s); temperature (kelvin, K); and amount (mole, mol). The base units can be modified by adding prefixes and suffixes, the most typical of which are mega (106, M); kilo (103, k); centi (10-2, c), milli (10-3, m), micro (10-6, m), and nano (10-9, n). Conversion factors are used when necessary to convert between the various units. Examples for length and volume (with derived units of length cubed) include:

1 m = 100 cm = 1000 mm

1 m3 = 1000 L (where L = liter)

1 L = 1000 cm3 = 1000 mL

Significant figures are those which have been accurately derived by careful measurements. The number of significant figures in a measured value is equal to the number of digits known for certain plus one that is not totally certain. The higher number of significant figures, the greater the degree of precision.

Scientific notation is a shortcut for writing very large or very small numbers. In science, the standard use is to write numbers to base 10, using exponents. As an example, an electron (a very small subatomic particle) has a mass of about 0.000 000 000 000 000 000 000 000 000 000 910 kg. In scientific notation, this number is rendered as 9.10 x 10−31 kg. Simple rules for working with exponents allow scientists to manipulate numbers easily when working with minute samples and very rapid reactions.

Friday, October 12, 2007

Chemistry is Your Friend; Introduction Lecture Notes


Chemistry AS403 – Notes for Introductory Lecture

Breathe. Breathe again. Now, repeat after me: “Remain calm, all is well.”

Welcome to Purgatory, or as I like to call it Chemistry for the Scientifically Reluctant. In the next few sessions, we will take an all-too-brief tour through the wonders of the chemical world.

Why should you come along for the ride? Because your entire existence – body, home, street, community, Earth itself – rises and falls on the basis of the chemical reactions that occur around and within you. Chemistry is your friend, even if you feel that chemistry class is not….

We’ll start the tour with INTRODUCTIONS. Your tour guide/persecutor is Brad Bolon, professional science geek (experimental pathologist and medical writer). I get to torment you with chemistry because

(1) I am a reasonably adept apprentice-level chemist, having about 1000 hours of lecture and lab in the field during the course of my professional education, and

(2) the other topic for this course was physics, which causes my brain cells to short-circuit.

You know who you are (I hope).

The next introductory item is to define HOW SCIENCE FITS INTO THE “REAL” WORLD. “Real” in this context means “material” or “natural” or “physical.” We will approach this question as a scientist would, by constructing a theoretical model off which to bounce our subsequent experiments. Based on lots of years in college (13!) and living in this world (45), my model for gathering and using knowledge emphasizes several different epistemologies. (An epistemology is a system by which we know that something is true.) There are several different epistemologies with relevance to the modern world, and most of us use more than one in the course of our daily lives. Examples include Revelation (“God told me so”), Reason (“it just makes logical sense”), and Tradition (“we have done it that way in the past”). The main epistemology of modern science is Empiricism (“we did an experiment, and this is how the world works”). Put them all together, and my current model of the world looks like the picture above.

To keep us on the same page, to me “hard” science means disciplines that emphasize physical experiments (astronomy, biology, chemistry, mathematics, medicine, physics) while “soft” science means fields where the results depend on unpredictable responses of individual human beings (economics, history, politics, psychology).

Please note that human beings are engaged in acquiring knowledge in all these realms. By definition, humans have opinions of their own, so subjectivity enters into everything that they do. The difference between experiment-based science (whether “hard” or “soft”) is that the only aim is objectivity, so the practitioners strive to remove as much bias as possible when doing their work.

The next introductory topic is to ACING THE HARD SCIENCES. Success in studying science is not easy – it’s not called “hard” science for nothing! – but the goal is attainable. All it takes is self-discipline and a logical approach. I used a 7-step process in my own science education, and I still use it daily as in my work as a scientist. The 7 keys are simple, not rocket science:

(1) Read the textbook the night before class. Yep, I hate to break it to you, but science classics are almost always textbooks. The reason is that science builds on itself over time. In general, about 50% of the stuff printed in current science magazines will prove to be wrong a decade or two from now, while the principles in modern textbooks represent concepts that most scientists believe to be true. So why read the textbook before class? Remember, science builds on itself – in this case, by repetition. The more times you are presented with a concept, the better you will understand it and recall it.

(2) Annotate what you have read. Take notes in the margin of the book or on a separate sheet of paper. Ask questions. Write your own lecture. The act of writing helps your brain to better remember what you have read.

(3) Listen to the lecture. This key is simple, if you show up and maintain some degree of consciousness. It’s even easier if you have read the book before coming to class….

(4) Read the textbook a second time. Not to be a nag, but repetition is good when studying science.

(5) Do the homework. The professor did not dispense problems to you just to torture you. (That is just a side benefit.) The assignment was given because the only way to truly understand a scientific principle is to work with it.

(6) Read more stuff. Don’t just read the assigned pages in the textbook. Read ahead, or reread relevant pages from previous chapters. Look for other presentations regarding the same topic on the Internet. The idea is to give your brain as many different versions of a new principle as are necessary for the concept to finally penetrate.

(7) Repeat as needed. (Duh.)

The thing about science is that it really is hard. People don’t subject themselves to this degree of torture voluntarily unless they are geeky enough to really enjoy the challenge. Maybe you qualify as a science geek, maybe not. Regardless, don’t make the task more difficult on yourself than it has to be.