Just Only Blog

September 2, 2010

Science and Technology Lecture – NWU – Sept. 7

Disaster in the Gulf

On April 20, 2010 the explosion and sinking of the oil rig Deepwater
Horizon in the Gulf of Mexico marked the beginning of what would become the
worst environmental disaster in U.S. history. With an estimated 215 million
gallons of crude oil spewed into the gulf over 87 days, the devastation to
the regions wildlife is unparalleled. Although clean-up operations are in
full swing, marine and plant life are suffering in a region that many fear
will never be the same again.

Dr. Ilze Berzins and Ken Ramirez from Chicago’s Shedd Aquarium will discuss
one of the nation’s richest environmental regions and what its future holds
at the Chicago Council on Science and Technology lecture on Sept. 7 at the
Northwestern University Chicago Campus, Baldwin Auditorium, 303 E. Superior
St. Reception and registration begin at 5 pm and presentation at 6 pm. Cost
is $10 in advance and $15 at the door. Cost for students is $5.
c2st.org

August 23, 2010

Survey of Organic and Biochem Begins…

Today we met for the first time. We introduced ourseleves and went over the website. We then launched right in to the chemistry of carbon. So what’s so special about carbon? One point that was made is that it has too many electrons to lose them all from its valence shell and not enough to gain them all to end up with the desired octet (8) so it has to share electrons – and does this by making four bonds. There are several ways this can occur – four single bonds, two double bonds, two single bonds and one double bond, one single bond and a triple bond – and all of these strategies are used. There are over 6 million organic compounds that have been identified and over 2 million have been synthesized in an organic laboratory.

We learned that carbon forms chains of atoms – straight chains, branched chains, and even rings. Organic compounds all contain carbon – but what else in in them? Well they typically include hydrogen and in many cases oxygen and/or nitrogen. Organic molecules may even have phosphorus, sulfur or any of the halogens attached to the carbon chains.

We began to talk about functional groups. You need to memorize them and learn to recognize them in molecules. They include the alcohols, aldehydes, ketones, esters, ethers, amines, amides, and others. They are printed on the back cover of the textbook. I found this page:

http://cactus.dixie.edu/smblack/chem1010/lecture_notes/2C.htm

it looks like fun and has some cute pictures.

Please read chapters one and two and PLEASE read the syllabus so you know how to prepare for class – we will continue on Wednesday. See you then.

August 16, 2010

Classes Begin Soon

Chemistry 212, Survey or Organic and Biochemistry, begins on Monday, August 23rd at 12:30 pm. We will review some General Chemistry and cover Chapter One and most of Chapter Two.

On Tuesday, August 24th Chemsitry 203, General Chemsitry II begins with a big review of General Chemistry I. I recommend that you review the Learning Outcomes for General Chemsitry I and review any topics that you may have forgotten.

The Sunday course Chemistry 100/121 Basic Chemsitry does not begin until September 12th. Please purchase your lab notebook before coming to class. You will need it the first day. Also I suggest you bring healthy snacks. It is a long day.

I look forward to seeing you all in class!

Good-Bye to the Summer

Here’s a good of happy successful student from this summer’s General Chemistry class. It isn’t easy taking chemistry in 8 weeks. These folks were in class four days a week from 8 until noon.

class picture

July 8, 2010

Qualitative Analysis Lab Posted (and some thoughts about Quantum Theory)

The Qualitative Analysis Lab is now posted. Log into the student area and go to the laboratory resources.

Today we began the study of atomic orbitals and periodic properties. I hope you all can explain why the chlorine atom is smaller than the sodium atom but the sodium cation is much smaller than the chloride anion. We looked at the shapes of the orbitals the: s, p, d, f orbitals (so please don’t freak out).

You should be able to draw the s, p and d orbitals. We discussed the Aufbau principle of filling atomic orbitals. You should be able to write electronic configurations (1s² etc.) for any element up to Xenon. One way to visualize the atomic orbitals is to use the Orbitron. Be sure to click on the different tabs: wave function, electron density, etc.

We haven’t talked about Schrödinger’s Cat so I hope you will watch this video. This is a very famous gedanken (thought experiment) that underscored the odd behavior that occurs at the quantum level of matter. This little experiment has made it’s way into popular culture so it is useful to have some idea what it is all about.

Next week we will discuss bonding, shapes of molecules, and molecular orbitals. Exam Two is on Thursday July 15th. Please be aware that Exam Three comes just one week later on July 22nd.

July 6, 2010

Back After a Long Weekend

Today we carefully went over the last two quizzes. The gas law quiz will be repeated tomorrow after class for anyone who hopes to earn a better score. The key point is that it is important to classify a problem type to know how to proceed. The main three types of gas law problems are ones based on the combined gas law (changes in conditions), ones based on the ideal gas law (usually combined with stoichiometry), and ones about density (learn the density equation).

The thermodynamics quiz was a bit better but many errors were made from a kind of carelessness. It is very important to order your thoughts and to order your work – take up the space you need.

After working on the quizzes for awhile we took a sparkler break. The chemistry of fireworks typically involves a strong oxidizing agent like potassium chlorate or potassium nitrate. Both of these provide oxygen that is then used to support the combustion of other materials.

After our break it was back to quantum chemsitry. You should know the three main experiments that could not be explained by classical physics, the ten scientists and their major contribution to atomic theory, and the rules for the four quantum numbers: n, l, m_l, and s. Each quantum number tells us something about the electrons in orbitals: size, shape, orientation and electron spin. The contours we see for these orbitals are deceptive – the orbitals are probability equations. They predict the probablity of finding an electron in a certain place. The electrons have specific energies, quantized energies. They move from one orbital to another by the absorption and emission of photons. (We also looked at the vocabular of light interactions with matter.)

All in all it was a very busy day.

July 2, 2010

Photo from the lab

Iodine in immiscible solvents Thanks to Meridith for this beautiful photograph taken during laboratory. This shows the chameleon-like behavior of iodine – one color in a polar solvent (dark orange) and a different color in a non-polar (hexane) solvent – deep violet. These different colors arise as a result to ligand field interactions with d-orbitals of iodine. Ligand field interactions are discussed in Chemsitry 203.

Iodine was first discovered in 1811 and named for its beautiful violet color (iodes means violet in Greek). Iodine is frequently used as an antiseptic agent. Tincture of iodine is a solution of iodine in ethanol.

“One day in 1811, Courtois made a mistake. He added too much sulfuric acid to the mixture. He was amazed to see clouds of beautiful violet vapor rising from the mixture. He decided to study the new material. Eventually, he proved it was a new element. He named the element after its color. In Greek, the word iodes means ‘violet.’”

Read more about iodine at Chemsitry Explained.

June 28, 2010

Chemical Reactions

Today we took a look at a worksheet about writing chemical equations from words.

The answers are available but please do as much as you can before looking at them.

Here’s an interesting video called Dangerous Science about chemistry sets in the present and past.

June 23, 2010

Lots of Demos

Over the past three classes many demos have been performed. Most of these are on youtube. Here are some links:

Purple Iodine Vapor

Fire Ice

The following link is to a video that was done for an AP chemistry class two years ago or so the young videographer says. I do NOT recommend trying this because it is becoming increasingly illegal to explode anything in public places and, well, you would never do this indoors except under controlled laboratory conditions. Having said this – this video is being watched by young people – note the misspelled words (thier) and the young hands in the video – and it is important to understand this kind of chemistry that is easily available to the public – as failure to understand it has resulted in injuries. As we learned in class, Drano contains caustic lye and solutions of Drano can easily damage any exposed skin they contact.

Drano

Pay particular attention to the use of aluminum, a very active metal but only when the outer coating of aluminum oxide is removed.

We’ve been studying gases, especially gas stoichiometry. The exam is tomorrow and covers material in Chapters 1-5. I’ve noticed that folks are getting much better with the polyatomic ions. I will be holding a problem solving session tonight in Room 3162 at 7:40 pm. The class I am teaching tonight finishes at 7:30 pm.

June 18, 2010

The basics are essential but lets move on to gases…

Today I explained that the foundation for learning chemistry is understanding the lexicon – and that means knowing the names and formulas of common chemical compounds. Knowing that zinc forms a 2+ ion and that lead forms a 2+ and a 4+ ion is essential to writing products for chemical reactions. Knowing a sulfate from a phosphate gives you fluency to easily write formulas like lead(II) sulfate and copper (I) phosphate. Memorization takes time – but once it is accomplished you will be free to think about other aspects of chemistry.

Online flash cards may help.

We will be retaking the stoichiometry quiz after class on Monday. The stoichiometry map is another essential tool for successful problem solving. Whatever information you are given to begin a problem you must be able to plot a route to the desired information about an unknown. This process involves many small steps that are taught independently such as how to convert some volume of a pure liquid to mass, or how to differentiate a pure liquid from a solution (where molarity is used). To help develop skills in solving stoichiometry problems you must practice, practice, practice…

If you do a search for “stoichiometry problems” on the Internet you will find there are many, many worksheets available – such as this one.

We started talking about gases and gas laws. The combined gas law P₁V₁/T₁=P₂V₂/T₂ and the ideal gas law PV=nRT are used to solve basic gas law problems. We reviewed these equations and learned how to calculate the density of any gas. We talked about sulfur hexafluoride, a potent green house gas.

Jay Leno is playing with sulfur hexafluoride in this video – notice how long the effect lasts. It takes time to get sulfur hexafluoride out of the lungs once it enters. Even though sulfur hexafluoride is non-toxic I don’t recommend this experiment.

Sulfur hexafluoride became a problem for Nike when its potent greenhouse properties were realized.

Sulfur hexafluoride is just one gas with interesting stories. You should learn the properties of these common gases: carbon dioxide, carbon monoxide, sulfur dioxide, nitrous oxide, nitrogen dioxide, hydrogen, helium, nitrogen. Fill out the Gases: Descriptive worksheet before Tuesday as we will discuss this in class. You can easily find information about all of these gases on the Internet. There are usually some interesting videos showing gas behavior and other demos.

On the day of the exam – Wednesday – you should turn in your homework notebook and it should be completed through assignment 11.

And please come prepared for laboratory on Monday – it is a great lab but you must know what you are doing or it could be dangerous. Read the lab ahead of time – it is in the laboratory textbook but you can buy it as a single lab from Centage Brain. Check the syllabus to see which experiments we are going to do this summer.

Older Posts »