Main Sequence     Overview Cycle     Interdisciplinary Discussions     Verbal Reasoning     Essay

Module 7 - Thermodynamic Systems - Part Two

Last module, in part one of our discussion of thermodynamics, our main sequence topics were Heat & Temperature, The Ideal Gas and Kinetic Theory, The First Law of Thermodynamics, Stoichiometry and Thermochemistry. We learned how to describe a system comprised of an enormous number of particles which may exchange heat with its surroundings governed by conservation of energy. We learned how to describe energy transfers and account for the balance of matter and conservation of energy between a system and its environment.

This module we ask ourselves what makes a transformation spontaneous? Why are some kinds of transformations more likely than the reverse process? We are making a conceptual transition across the boundary from mere Thermochemistry to the full Chemical Thermodynamics. In addition to Chemical Thermodynamics, we will also be reviewing Chemical Kinetics this module. In Chemical Thermodynamics, we are interested in the comparison between the reagents and products as two possible states of the system. In Chemical Kinetics, we are also interested in the pathway between them.

Module 7 - Overview

Main Sequence - The Second Law of Thermodynamics & Heat Engines, Chemical Thermodynamics and the Equilibrium State, The States of Matter, The Physical Properties of Organic Compounds, and Chemical Kinetics.

Overview Cycle - This is the first module in which we find ourselves responsible for the outlines of all four disciplines: Physics, General Chemistry, Organic Chemistry and Biology.

Interdisciplinary Discussions - An intense and challenging set of discussions designed to help you integrate a great deal of physics and chemistry.

Verbal Reasoning and Essay - One more module on the regimin of reading program, exercise, and writing assignment. Next module, I promise, something different!

Module 7 - Main Sequence        { 12 - 15 hours }

What makes an event irreversible? What if events in the forward direction were just as likely in the reverse? In such a universe, time would have no meaning. Everything which could happen in one direction could just as likely unhappen. The Second Law of Thermodynamics describes how it is that our universe does not work in this manner. The Second Law of Thermodynamics describes a quantity as always increasing in the universe, the entropy, a statistical quantity that the word 'disorder' can almost capture.

This module we will locate the Second Law of Thermodynamics in its traditional context within Physics, and subsequently in Chemistry, where we will bring the ideas to fruition in our chapter, Chemical Thermodynamics and the Equilibrium State. This module we will also involve the topics: States of Matter and Physical Properties of Organic Compounds, as fields for the discussion of the ideas of spontaneity and equilibrium.

Finally, our remaining main sequence topic this module will be Chemical Kinetics. Chemical Kinetics is the study of the rate of chemical reactions and reaction mechanisms. While Chemical Kinetics is intimitely related to Chemical Thermodynamics, it is very important when discussing chemical reactions to understand how the path dependent propositions of Chemical Kinetics differ from the path independent concepts of Chemical Thermodynamics and Equilibrium. A catalyst, for example, may increase the rate of a chemical reaction, but it will not shift the position of equilibrium.

The Second Law of Thermodynamics on the MCAT

The Second Law appears in direct fashion with moderate frequency on the MCAT. For example, a physical sciences passage on a chemical reaction or thermodynamic process may pose a question as to whether a particular change corresponds to an increase or decrease of entropy. Bear in mind, though, that the direct importance for the test, with regard to this topic, is dwarfed by the significance of the Second Law of Thermodynamics for understanding the physical and biological sciences in a rich way.

Focus please! This is an important conceptual bridge which only a minority of premedical students will ever cross, where you can not only sieze an advantage over the competition, but also gain a foothold into a much deeper understanding of science, which will make the universe more coherent to you for the rest of your life. Most of your peers don't have a good conceptual feel for the Second Law. Believe me. I have worked with many premedical students. I hate to say it but this means that they don't really understand chemistry or biology, in my opinion, no matter how good their grades have been in college. Start thinking about the 2nd law as a walking around habit. Walk around with it. Be patient. Always look for another step into a deeper understanding. It will be worth it!

Learning Goals for the Second Law of Thermodynamics and Heat Engines

Suggested Assignments

Chemical Thermodynamics and the Equilibrium State on the MCAT

On the MCAT, although you probably will run into a Le Châtelier's Principle question or two, the importance of this topic is very great besides direct questions on the MCAT because the concepts discussed here are the scaffolding on which much else is built. Most students find chemical thermodynamics to be a very abstract subject. I think this unfortunate situation occurs because of the way that chemical thermodynamics is approached in undergraduate general chemistry, without physics to make it intuitive and biology to make it concrete. If you approach chemical thermodynamics, though, with a basis in force and energy, you can relate the internal energy changes driving heat flow and entropy change to a fundamental understanding of the particle level of substances. Furthermore, when you bring chemical thermodynamics to your understanding of biochemistry, your appreciation of life processes will become much more coherent and much more interesting. This is the kind of intuitive feel for science that the MCAT writers are ultimately looking for with their exam.

Learning Goals for Chemical Thermodynamics and the Equilibrium State

Suggested Assignments

States of Matter on the MCAT

Content such as phase equilibria diagrams, the behavior of real gases, and the vapor pressure are MCAT favorites. With liquids, surface tension and capillary action have been on many exams. Occasionally, an MCAT even may expect familiarity with the terminology of crystal structure in solids. In other words, this is core general chemistry knowledge. You should be prepared for questions from this material on your exam.

Learning Goals for States of Matter

Suggested Assignments

Physical Properties of Organic Compounds on the MCAT

Understanding how functional groups affect the physical properties of organic compounds is of primary importance to laboratory organic chemistry. Furthermore, it is an important conceptual bridge from organic chemistry to biochemistry and cell biology. You definitely need this understanding to be able to grasp protein folding, for example, or the structure of biological membranes. This is a priority for the MCAT. You can expect both direct and indirect questions. Straightforward questions asking for a comparison of solubilities are common, for example, or questions involving similar reasoning in a more advanced biological context.

Learning Goals for the Physical Properties of Organic Compounds

Suggested Assignments

Chemical Kinetics on the MCAT

Chemical Kinetics problems involving number crunching are rare on the MCAT. However, conceptual questions involving Chemical Kinetics are very common on the test. Chemical kinetics lends itself especially well to the MCAT passage format where passages presenting data can lead to questions involving inference of reaction order, for example, or where the application of kinetics principles allows one to judge among various reaction mechanisms. In the construction of multiple choice questions, the MCAT writers are also fond of questions that make sure students don''t confuse the propositions of Chemical Kinetics, which depend on the reaction pathway, with the concepts of Chemical Thermodynamics, which do not depend on the mechanism.

Learning Goals for Chemical Kinetics

Suggested Assignments

Module 7 - Overview Cycles        { 2 hours }

A residential builder developing a neighborhood would not build one house, finish the landscaping of that one, and only then extend the road another 20 meters, and begin clearing the next lot. The developer would not wait until the very end to see what the map of their neighborhood looks like. One of the first tasks would be to survey the entire development and build the roads throughout the development. Building the individual houses, all the way to the installation of wiring and putting in windows, is analogous to our Main Sequence treatment of the knowledge. Our Overview Cycles are analogous to surveying the whole.

Now is the time in the learning program to begin holding yourself responsible for the outlines of all four sciences at the main topic level. Learning these outlines will perform many valuable functions in the context of the learning program and on exam day. In the learning program, they will help you get your mind around the challenge ahead. Instead of the content you haven't mastered yet stretching oppressively off into the foggy distance, you can get your mind around the weak areas, and give the unknown boundaries. You will start to see that for each topic, there are a half dozen things you really need to know. This allows you to approach your learning project with goal orientation. You can self-assess your understanding of each topic as you go through sequence of familiarity to retention, understanding, and knowledge.

Furthermore, by providing structure to your knowledge base, you will be able to access concepts easily. This will not only be invaluable on the exam, but it is a key to interdisciplinary understanding, to be able to see the scientific disciplines in the light of each other, which is the key to conceptual intuition and a superior MCAT.

The Four Disciplines

Study the outlines below of Physics, General Chemistry, Organic Chemistry and Biology. Read them slowly and carefully. Try to picture the model case phenomena of importance within each area. Try to recount the subtopics, which aren't shown, especially of the material we have already covered in the Main Sequence. Instead of the accustomed learning process in which you add new pieces of material to a series of concepts that grows longer each module, think of studying for the MCAT as a planned process of laying down a comprehensive foundation and elaborating a mental structure through repetition and articulation, a structure that becomes more rich, full, and interrelated as the course progresses.

MECHANICS Kinematics Newton's Laws Work, Energy, and Power Momentum and Impulse Rotation Harmonic Motion Elastic Properties of Solids Fluid Mechanics WAVES Waves GRAVITATION Gravitation THERMODYNAMICS Temperature and Heat Flow The Ideal Gas and Kinetic Theory The First Law of Thermodynamics The Second Law of Thermodynamics and Heat Engines ELECTRICITY & MAGNETISM Electricity DC Current Magnetism Electomagnetic Induction AC Current LIGHT & OPTICS The Properties of Light Geometric Optics Wave Optics MODERN PHYSICS & NUCLEAR PHYSICS Modern Physics Nuclear Physics

THE STRUCTURE OF MATTER Atomic Theory Periodic Properties The Chemical Bond Intermolecular Forces STOICHIOMETRY Stoichiometry CHEMICAL THERMODYNAMICS AND CHEMICAL KINETICS Thermochemistry The States of Matter Chemical Thermodynamics and the Equilibrium State Chemical Kinetics SOLUTIONS AND AQUEOUS SYSTEMS Water Solutions Acids and Bases OXIDATION REDUCTION AND ELECTROCHEMISTRY Oxidation/Reduction Electrochemistry COORDINATION CHEMISTRY Coordination Chemistry

ORGANIC REACTION CHEMISTRY Reactions of Alkanes Reactions of Alkenes Reactions of Alkynes Reactions of Alkyl Halides Reactions of Allylic and Benzylic Conjugation Reactions of Aromatic Compounds Reactions of Alcohols and Ethers Reactions of Aldehydes and Ketones Reactions of Carboxylic Acids and Derivatives Reactions of Amines Reactions of Organic Phosphorus Compounds Reactions of Organic Sulfur Compounds ORGANIC CHEMISTRY CONCEPTS Functional Groups in Organic Chemistry Conformations of Organic Molecules Stereochemistry The Physical Properties of Organic Compounds Organic Acids and Bases Nucleophiles and Electrophiles Intramolecular Cationic Rearrangements Reactions with Radical Intermediates Conjugated π Systems and Aromaticity Oxidation/Reduction in Organic Chemistry Molecular Spectroscopy

BIOMOLECULES Proteins Carbohydrates Nucleic Acids Lipids THE CELL Biological Membranes The Prokaryotic Cell The Eukaryotic Cell BIOENERGETICS AND BIOSYNTHESIS Bioenergetics and Cellular Respiration Photosynthesis  not on MCAT Biosynthesis of Macromolecules Integration of Metabolism GENETICS & REPRODUCTION Gene Expression Cellular Reproduction Mendelian Genetics Recombination and Mutation The Molecular Biology Laboratory Human Genetics DIVERSITY OF LIFE Viruses Monera Protista Fungi Plants  not on MCAT Animals Animal Development and Embryology Mammalian Tissues and Histology HUMAN PHYSIOLOGY The Nervous System Sensory Systems The Endocrine System The Musculoskeletal System The Cardiovascular System Blood The Respiratory System The Lymphatic System and Immunity The Urinary System The Digestive System and Nutrition The Reproductive System EVOLUTION AND ECOLOGY Populations Evolution Ecology

Overview Cycle - Learning Goals

Assignment

Module 7 - Interdisciplinary Discussions        { 3 hours }

The Interdisciplinary Discussions this week are devoted to helping you the Second Law of Thermodynamics, Chemical Thermodynamics and the Equilibrium State in an intuitive, concrete way. It took me years to develop a way to get this stuff across to students in small group teaching, and I think these discussions can help you. You find yourself, at this stage in the learning program, in Chemical Thermodynamics and Chemical Kinetics at the crossroads of physical and biological science. The thermodynamic concept, entropy, for example, is a very abstract subject for most students, and at the undergraduate level, very few premedical students develop much of an understanding frankly. Be patient with yourself and you can get past your peers. I guarantee it. Sustain the thread of conceptual thought and active imagination and really break through. This is a key moment in the course. When you can picture a chemical change in terms of internal energy at the particle level and connect that to heat flow between a system and its surroundings, you have the first step, a you have a thermochemical sense. Next, work to get from Thermochemistry to Chemical Thermodynamics and Equilibrium. Find the conceptual bridge from enthalpy change to free energy change. This bridge is not a formula. It is a structured ability of conceptual imagination. Locate the basis of spontaneity in the Second Law and place it in the chemical context. If you can do this, Biochemistry will become an intellectual feast and your understanding of life processes will leave you gobsmacked.

Interdisciplinary Discussion - Learning Goals

Suggested Assignments

Module 7 - Verbal Reasoning        { 2 - 3 hours }

Verbal Reasoning Tip of the Week

Watch out for wrong answers designed to entice you to answer what your own opinion is instead of the author's. The question prompt will not say, 'according to you'. It will say, 'according to the author'.

Verbal Reasoning Assignments

Module 7 - Essay        { 2 hours }

At this stage in the course, you have written six MCAT essays. In module 2 we discussed how to structure a unified critical MCAT essay. If you would like to review the advice from that module, here is a LINK to that discussion for a quick review.

Essay Assignments