Explore BrainMass


Entropy is a measure of the number of specific ways in which a system can be arranged. It is considered to be the measure of disorder. In an isolated system, entropy never decreases because isolated systems spontaneously evolve towards thermodynamic equilibrium which is the state of maximum entropy.

Entropy is a thermodynamic quantity that helps to account for the flow of energy through a thermodynamic process. Originally, entropy was defined by a thermodynamically reversible process as

ΔS = ∫(dQrev)/T

where entropy is found from the uniform thermodynamic temperature of a closed system divided into an incremental reversible transfer of heat into that system.

Entropy in thermodynamics is a non-conserved state function that has major importance in the science of physics and chemistry. The concept of entropy evolved in order to explain why some processes occur spontaneously while their time reversals do not. Systems tend to process in the direction of increasing entropy. Chemical reactions cause changes in entropy and entropy plays an important role in determining which direction a chemical reaction spontaneously proceeds.

Entropy change of the universe

5.9 Two equal quantities of water, of mass m and at temperatures T1, and T2, are adiabatically mixed together, the pressure remaining constant. Show that the entropy change of the universe is [see the attachment for the equation] where c_p, is the specific heat of water at constant pressure. Show that [delta]S >= 0. (Hint: (a

Probability and Entropy

What is the change in entropy for the following "reactions"? For the purposes of this exercise treat the pennies as if this was about molecules and use Bolzmann's constant in your calculations. a. 100 pennies that were all arranged to be heads facing up and changed to all have tails facing up. b. 100 pennies that were arranged

A descriptive account of how to deduce the magnitude of the entropy changes by considering two processes, the melting of 0.1 kg of ice to water and the heating of the water from 0 to 25 degrees C; a ;a latent heat change and a specific heat change

100 g of ice is melted at 0 degree C, and the resulting water is warmed to room temperature (25 degree C). Calculate delta S (change in entropy) for this whole process and comment on the relative magnitude of the entropy changes for the two steps. Explain the sign of delta S.

Entropy increase of Carnot engine operating on methane

A Carnot engine operates on 1 kg of methane, which we shall consider to be an ideal gas. Take γ = 1.35. The ratio of the maximum volume to the minimum volume is 4 and the cycle efficiency is 25 percent. Find the entropy increase of the methane during the isothermal expansion. γ = cp/cv η = .25 = 1-T1/T2 I know to co

Change in entropy that the Universe has to suffer from Ice Cream melting?

If a carton of ice cream is left out of the freezer overnight and completely melts, how do I figure out what the change in entropy that the Universe has to suffer because of this? The mass of the ice cream = 1 kilogram Original temp. of ice cream was 0 deg. Celsius, but had heated up to 25 deg. Celsius (room temp.) The spec

change in entropy of the ice/water

A one kilogram block of ice melts at 0°C and slowly warms up to the room temperature 30° C. (a) What is the change in entropy of the ice/water? Here's what I did: L_ice = Q/m = 80 cal/g = 80000 cal/1 kg deltaS_ice = Q/T = (80000)(4.186)/273 = 334880 J/273 K = 1226.67 J/K L_water = Q/m = 540 cal/1 g = 540000 cal

Heat capacity and entropy

Experimental measurements of the heat capacity of aluminum at low temperature (below about 50 K) can be fit to the formula: See attached file for full problem description.

Microscopic Interpretation of Entropy

A box is seperated by a partition into two parts of equal volume. The left side of the box contains 500 molecules of nitrogen gas; the right side contains 100 molecules of oxygen gas. The two gases are at the same temperature. The partition is punctured, and equilibrium is eventually attained. Assume that the volume of the b