Thermodynamics(09-01-08->present)

Thermodynamics, which came from the Greek word "therme" meaning heat and "dynamis" meaning power, is a branch of physics and is used extensively in chemistry and biochemistry.It studies the effects of changes in temperature, pressure, and volume on physical systems at the microscopic scale by analysing the collective motion of their particles using statistics. Roughly, heat means "energy in transit" and dynamics relates to "movement"; thus, in essence thermodynamics studies the movement of energy and how energy instills movement. Historically, thermodynamics developed out of need to increase the efficiency of early steam engines.(http://en.wikipedia.org/wiki/Thermodynamics#The_laws_of_thermodynamics)



Thermodynamics has 3 Laws:



1. The first law states that the energy of the universe is constant. It can only be transformed from one form to another.(conservation of energy)

equation:

∆E = heat(q) + work(w)

where work = -P∆V and the -P is the opposing pressure

so the equation for this law is:

∆E = q - P∆V



2. The 2nd law states the ∆S (change in entropy) of the universe must always increase.(entropy)

to predict whether a reaction is spontaneous or not. There are things that we should follow:

• whenever the ∆G(Gibbs Free Energy) is negative, the reaction is spontaneous;


• the reaction is spontaneous at all times if ∆H and ∆G are both negative and only ∆S is positive;


• the reaction is spontaneous when the temperature is high and when ∆S and ∆H is positive;


• the reaction is spontaneous when the temperature is low and when ∆H, ∆S, ∆G is negative; and


• the reaction is nonspontaneous if only the ∆S is negative.

3. The 3rd law states that the entropy of a crystalline substance is zero at the absolute zero temperatue. (absolute zero temperature)