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Posted by on Aug 30, 2013 in Physical Chemistry, General Science | 3 comments

Physical Chemistry – Overview of Thermodynamics

In one example I use bond energies to calculate the energy per mole of sucrose and TNT (the explosive trinitrotoluene). Most students expect that TNT has more energy, but it turns out the two have about the same. So why is TNT an explosive (actually a conflagration)? TNT burns rapidly and involves a huge volume change. It is the rate of reaction (chemical kinetics) and the rapid volume change that causes the explosive damage. Then I can move to the thermodynamics overview.

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Posted by on Aug 6, 2013 in Physical Chemistry, General Science | 0 comments

Physical Chemistry—hotness and coldness

When I start into heat capacity I contrast the temperature of a substance with the feeling of hot and cold. A thermometer will tell you the temperature of a substance, but that does not tell you how much heat is present. If you touch something, you can tell if it is hotter or colder than your hand, but what about two substances at the same temperature?

Suppose outside it is -10 C (14 F) and there you find a piece of steel and a piece of Styrofoam. Which is colder? If you touch the steel it feels colder than the Styrofoam, but they are both at the same temperature. If you placed the steel on the Styrofoam, no heat will flow between them (Third Law of thermodynamics). Since your hand is much hotter than the objects, heat must flow from your hand into them.

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Posted by on Aug 2, 2013 in Physical Chemistry, General Science | 0 comments

Teaching physical chemistry–lecture recording?

Although the obvious “pro” of recording is to give students the chance to listen numerous times; review the material; and listen to missed lectures, there is a huge “con” and that is they skip class and opt to listen to my lectures at home. Last year the attendance dropped to half because lectures are available on line, but this year the time has been shifted to 8:30 a.m. from 10:30. I am going to predict that very few will want to attend at that hour.

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Posted by on Oct 26, 2012 in Quantum Mechanics Research, General Science | 0 comments

Spin and Quantum Computers

One day I am sure that physics will view Nature as real. Throughout history initial ideas of non-local effects, also called “action-at-a-distance”, have been repudiated and replaced with something more physically reasonable. The most well-known examples are the early attempts to understand gravity and electromagnetism. So it will be with non-locality between entangled particles.

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Posted by on Oct 11, 2012 in Quantum Mechanics Research, General Science | 0 comments

The Bloch Sphere and Spin in Quantum Mechanics

This complementary nature of states with non-commuting operators, (σX, σY ,σZ), is the basis for the Copenhagen Interpretation of Quantum Mechanics (CI). It states, basically, that if the Z states exist then the X do not, and vice versa. I would rather conclude that it is impossible to determine experimentally if spin has more than one axis of quantization.

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