Step 2: Change in temperature (Heating at constant volume) Step 1: Change in volume (Isothermal expansion from 0.500 to 1.000 dm^3)

Water, due to its hydrogen bonding that holds the molecules together, shows an entropy of vaporization higher than the majority of liquids.Ĭalculate the entropy change when Argon at 25 C, and 1.00 bar in a container of volume 0.500 dm^3 is allowed to expand to 1.00 dm^3 and is simultaneusly heated to 100 C. However, there are exceptions to this rule. According to Trauton's rule, a change in volume takes place when a liquid evaporates to become a gas, and all liquids can be expected to have similar standard entropies of vaporization. Trauton's rule specifically applies to vaporization. Table 3.1 gives us the standard entropies (and temperatures) of phase transitions, and table 3.2 gives us the standard entropies of vaporization of liquids. At the temperature where the transition is taking place, the heat transferred from the system to the surroundings is reversible because the two phases are at equilibrium. The entropy of matter increases as it changes from solid to < liquid to< gas. When matter changes phases, the order in which molecules are held together as well as the localization of energy changes. ** This is the equation for entropy change in a system whether the path is reversible or not because entropy is a state function.Įntropy Change for Reversible Phase Changes: As long as the initial and final states of a system are connected by any reversible adiabatic path, the entropy change is going to be zero.Įntropy Change for an Ideal Gase (Isotherm):

2 etc) Calculating Entropy Change in Specific Processesįor adiabatic changes, q=0 and the entropy change is 0. Dr Cooper's comments: Number fundamental equations (Eq.

Absolute entropy of argon