The Perfection of Gas and the Greatness of Organic Compounds

Just like Olympic judges, chemists have established a set of attributes that describe perfection so that we measure everything else relative to an impossible standard. The Ideal Gas is purely hypothetical; consisting of identical particles of zero volume with no intermolecular forces. This approach struck me as arrogant until I understood that Gas Laws that followed:

1. Graham’s Law: rate of movement is proportional to mass

2. Dalton’s Law: total pressure is the sum of individual pressures

3. Boyle’s Law: volume varies with pressure (at constant temperature)

4. Charles’s Law: volume varies with temperature (at constant pressure).

The early chemists weren’t just Photoshopping. By imagining perfection, they found a way  to describe reality.

The reality of my upcoming exam pushed me to finish the final chapter which was Organic Chemistry, the study of compounds that contain carbon. These compounds are deemed ‘organic’ because carbon was originally obtained from the remains of living things, like coal. The carbon atom of today is the backbone of thousands of compounds that keep us warm, healthy, clothed, and together. Travel and romance would be nothing without carbon.

What makes carbon great is its four outer electrons that are able to form single, double, and even triple bonds. And bond it does, creating almost endless chains of molecules that are used to make fuel, medicine, textiles, and adhesives. The same atom is responsible for the diamonds in my wedding band and the gasoline in my car.

Maybe perfection and greatness are closer than I imagined.

Next up: The Last Lap

Changes in Attitude, Latitude, and Phases

The weather this week really helped increase my study time. If I hadn’t had a dog to walk (or West Wing on Netflix) I probably would have finished the entire Chemistry section.

Energy can be put to many uses and this lesson was about using it to change phases of matter. We can calculate the energy (q) , or heat, required to change the temperature of any material with a simple equation:

q = (m) x (Cp) x (Change in Temperature).

Cp is a constant value related to the material, specific heat, and m is the amount of material, or mass. In other words, temperature changes linearly with heat, which is obvious and beyond boring.

What gets interesting is the action during phase changes. As the energy changes, there is no corresponding change in temperature. Boiling water will stay at 100 degrees Celsius and a slushy ice mix will stay at 0 degrees no matter how much heat is added. The temperature does not change because all of the energy is being used to pull apart the intermolecular bonds which, like bad habits, are tough to break.

The energy needed to muster through a phase change is ‘heat of vaporization’, ‘heat of fusion’, or sheer will power. It is substantially higher that what’s needed to change temperature. Only after all the ice is melted or all the boiling water is evaporated will the temperature once again rise in a linear but boring fashion.

There are two simple equations:

q = (m) x (heat of fusion) when moving from a solid to a liquid and

q = (m) x (heat of  vaporization) when moving from a liquid to a gas,

and I am struck by two simple truths:

1. It takes a lot less energy to change outwardly than inwardly.

2. Transformation starts at the smallest level and for a while there are no signs.

Next Up: The Perfection of Gas and the Greatness of Organic Compounds

Related Articles:

Energy, Balance, and Astrology

When was the last time that you were so enthralled that hours passed like minutes?

The Principal and Science Chair of Rockhurst High School allowed me to to observe an afternoon of chemistry classes this week. Michael Sullivan taught the same subject to three different classes (AP, Honors, and General) with such a variety of techniques that I lost count. It was equal parts push, wait, argue, understand, noise, silence, chaos and clarity. The pace was blinding. The energy was off the scale. The jokes, mostly from the students, did not stop. Correct answers were celebrated with desk pounding and wrong answers were acknowledged with forehead smacks. The young men came in small groups discussing local sports, NHS events, and Schrodinger’s cat. They left arguing the best titration techniques and the quickest way to determine if a reaction is endothermic or exothermic.

I was also captured this week by the concept and mechanics of Oxidation Reduction reactions. It is not an overstatement to say that every aspect of our lives is governed by the behavior of electrons. In many reactions, electrons stay with the atom that brought them, but in Redox reactions they jump ship, sometimes in droves. This flow creates electricity and this knowledge led to the invention of batteries and the field of Electrochemistry.

Unfortunately, the mechanics of balancing Redox reactions did not flow as easily as the concept, but my Libra nature would not rest until I mastered the 10-12 steps. I used Kahn Academy, two additional Chemistry textbooks, and even Chemistry Essentials for Dummies. At the end of the week, I could take apart molecules, describe the flow of electrons, add water or hydroxide as needed, and then finally put them all back together again.

Let the desk-pounding commence.

Life, Death, and Chemistry

Look around – can you imagine how many chemical reactions are happening before your eyes at this very moment? Some materials are synthesizing and some are decomposing. Some compounds are swapping molecules and some may combust. Without these reactions and our ability to predict them, there would be a smaller staff at Downton Abbey, tonic would stay fizzy, nausea would last, and the New Year would be quiet.

The most important example of synthesis occurs when hydrogen and oxygen molecules combine to make water. This is as simple and profound as creation itself. A less inspirational example of synthesis is the formation of tarnish that occurs when silver reacts with sulfur in the air to make silver sulfide. Chemists call this 2Ag + S —> Ag2S and Lord Grantham calls it a steady job.

A sad example of decomposition is the spontaneous decay of carbonic acid (H2CO3) into carbon dioxide (CO2) and water. This is why that large bottle of tonic that you have been saving for the summer G&T’s may ultimately disappoint: H2CO3 ——> CO2 + H2O.

The most interesting reactions happen when compounds swap, or replace, molecules to form new substances. Hydrochloric acid (HCl) in the stomach makes us queasy until calcium hydroxide (Ca(OH)2) arrives. Oh what a relief it is when the acid is neutralized into two products that are much easier on the stomach: calcium chloride (CaCl2) and water,  2(HCl) + Ca(OH)2 ———> CaCl2 + 2(H2O).

For sheer drama, however, no reaction can match combustion. Fireworks are made with gunpowder that produces  heat and noise and metals that produce color. Copper shows blue, lithium and strontium red, and magnesium and aluminum are white when combusted. Combustion reactions produce much more energy than is required to start them and they need a lot of oxygen. Drama turns to danger when materials spontaneously combust, which happens when enough heat is generated by the reaction to ignite the materials at hand. This can happen with the right combination of microbes, moisture, heat and hay.

The laboratory of my life got a lot more reactive this week as I am making plans to use my favorite Christmas gift:  a Chemistry Set with enough equipment and reagents to conduct 333 experiments. My husband (aka Santa) has offered to help me set up an area in the garage and has even volunteered to be my assistant on the condition that I call him ‘Igor’. It’s all about the chemistry.

Name and Number, Please

One advantage to on-line study is that I can do it anywhere, especially if the internet is free and the caffeine is plentiful. My over-sized laptop has traveled from the Jesuit-like austerity of the Clinton Public Library cubicles to the KC Plaza coffee shops full of selfie-taking Moms, drowsy homeless people, and nervous students. The first time I learned Chemistry I carried 3×5 index cards.  They were light and required only good handwriting and no connection, except to my memory.

This week I learned how to remember the names of compounds. The rules are almost as easy as The Name Game, but not quite as singable. The positive element goes first, followed by the negative, plus ‘ide’. HCl = Hydrogen Chloride. Ratios are identified by the Greek prefixes mono through deca. SF6 = Sulfur Hexaflouride. Suffixes vary by amount of oxygen (‘ate’ through ‘ite’) and acids end with ‘ic’.

My laptop even traveled to the Learning Forward Conference in ice-bound Dallas this week. I learned about teaching and the support that teachers need, but often do not receive, in order to grow as professionals. Overall the conference was great, even though I was disappointed to learn that the 4C’s of 21st Century Learning* do not include Chemistry.

However, in two days I was fortunate to have three elemental teachers that are gifted in three very different ways and the combination was perfect. Thanks go out to my very own poly-atomic learning compound: SkAdF2 = Sarann Difullanide. I hope to make another batch of you in my lab very soon.

Life, Death, and Chemistry

*Creativity, Communication, Collaboration, and Character

 

Castles in the Air

As with friends, families, and communities, the truly interesting behavior starts once bonding has occurred and the structure is in place. The relationship dynamic for electrons is called “Valence Shell Electron Pair Repulsion”, which is a term that will never be hashtagged ever. VSEPR means that once electrons have bonded to form pairs, they move as far apart as possible from other electron pairs. This gives rise to many different structures as the pairs jockey for space. It’s important to remember that these structures are three-dimensional even though we draw them with dots, arrows and equations.

For example, the molecule SCL4 has five electron pairs around the S atom which creates a Trigonal Bipyramid like this:

240px-Trigonal-bipyramidal-3D-balls

The molecule XeF4 has six electron pairs around the Xe atom which creates an Octahedral structure that looks a lot like the jacks that we used to play with:

th8YRUZDR0

I learned 10 structures this week, ranging from the lowly Linear, Bent, and T-Shape all the way to the magnificent Tetrahedral and Square Pyramidal. I also learned that these bonds build more than just beautiful structures. The nature of the bond has a direct effect on the physical properties of the compound. Strong bonds cause high melting points, high boiling points, and low vapor pressures. I wonder what new materials are out there waiting to be created with just the right combination of structure and strength?

Tomorrow I am travelling to attend a conference about learning. I hope to eventually build just the right classroom combination, even though right now the areas of teaching and learning seem more like alchemy – all mystery and magic – and less like the balanced and predictable study of electrons that I find so comforting.

Next Up: Name and Number, Please

The Ties That Bind (or not)

The ways that atoms bond to make molecules, polymers, and metals are as wondrous as the ways that people bond to make friendships, marriages, and communities. The strongest tie happens when one atom gives an electron completely and unconditionally to another. The result is that the giving atom becomes positively charged and the recipient becomes negatively charged, so they become irresistible to each other. This type of bond is called Ionic by chemists and Lifelong Love by Bell Hooks. Once these molecules form, they remain intact and are not available to bond with other molecules.

Another type of bond occurs when atoms simply share a pair of electrons. This means that they have some common platonic interests. If the sharing is equal, the bond is Covalent and if the sharing is unequal, the bond is Polar Covalent.

Bonding gets really interesting when molecules form but they still have some extra electrons, or not enough. This causes them to bond in infinite arrays with other molecules that are seeking or giving electrons. This is how polymers and metals are formed. In the case of polymers, the pattern of electron bonding is rigid and repeating. This is why diamonds are so brittle. In the case of metals, electrons are shared between molecules freely and magnanimously. This is why metals are good conductors.

I have had to re-build many bonds this year. I am happy that that they now know me by name at the post office, bank, and hair salon and that neighbors walk in our kitchen without knocking. However, I am still looking for others that are on an on-line journey to become a teacher and I’ll gladly give an electron or two when I find them.

Next Up: Castles in The Air