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Posted by on Jun 4, 2012 in Physical Chemistry | 1 comment

Physical chemistry course outline on intrinsic spin angular momentum.

The lectures will be recorded at the Indian Institute of Technology (IIT) Madras which is part of the NPTEL program. A major goal of NPTEL is to raise awareness and improve scientific and technological education throughout India by use of multimedia. I will be giving a series of lectures on basic spin theory for chemistry and physics undergraduate students who have a basis in quantum mechanics; know of spin and its importance; and want to go deeper.

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Posted by on Dec 19, 2011 in Physical Chemistry | 0 comments

Entropy (Part 6): Randomness and ensembles

After rolling 2, 3, 4, 10 and Avogadro’s dice, as seen in the entries below, it becomes clear that the most random states (most number of ways of rolling a number) always dominate while those with fewer arrangements occur less frequently: 1 Entropy: Randomness by rolling two dice 2 Entropy: Randomness by rolling three dice 3 Entropy: Randomness by rolling four dice 4 Entropy: Randomness by rolling ten dice 5 Entropy: Randomness by rolling Avogadro’s dice In this final entry of randomness and entropy, the concept of an ensemble is discussed. We are using a die to represent a particle that has six states that come up randomly.  Hence we have treated systems with 2, 3, 4, 10 and Avogadro’s constant (let’s use 1023) of particles (dice) and have shown that as the number increases, the total number of accessible states, is given by 6n. Clearly the number of states in Avogadro’s case is  61023 : an enormous number!! If you start to roll this many dice, every roll gives...

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Posted by on Dec 8, 2011 in Physical Chemistry | 0 comments

Is Learning Chemistry difficult? Are you stressed about it?

Exam time is coming and we have 1,100 freshman chemists getting stressed and nervous, so this is for them.

You need “stress” in your live. No stress would mean you would stay in bed all day. Well I’m a chemistry prof and like physical chemistry, and not a psychologist, but over the years you get to know students worries.

There are two types of stress. There is bad stress (“I’m scared”, “I’m dumb” “It is too hard?”) and there is good stress (“Great day, gotta get up!”, “I really want to understand stuff” “I am looking forward to tonight, so got to look good.”)

Use the good stress.

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Posted by on Nov 21, 2011 in Physical Chemistry | 0 comments

Entropy (part 3): Randomness by rolling four dice

The basic idea is that a physical system has many different arrangements (states) of particles which are consistent with some macroscopic quantity, like the temperature. Boltzmann found that out of all possible ways those particles can be arranged, only those that are consistent with the actual temperature need be considered. The chance of any other arrangements is negligible in comparison. Rolling dice illustrates this nicely.

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Posted by on Nov 14, 2011 in Physical Chemistry | 0 comments

Entropy (Part 2): Randomness by rolling three dice

it is suggested the difficulty students have in understanding that entropy is a measure of randomness can be approached by rolling dice. In the first entry two dice were rolled but in that case there are only 36 arrangements and 10 outcomes (rolls from 2 to 12). This does not show that the most random state dominates (i.e. the one with most number of arrangements consistent with a roll of 7) . To show that more dice need be rolled. In this entry three dice are shown to have more randomness in the outcomes (3 to 18).

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