12 Entropy

Ludwig Boltzmann was an Austrian physicist and philosopher. His famous formula for entropy can be found on his tombstone at the Vienna Central Cemetary (Wiener Zentralfriedhof).

i. Briefly explain what entropy is and find an example in your everyday life. Use Boltzmanns entropy formula for your explanation.

ii. Think about the sign of Sm. Briefly explain the nomenclature of signs in thermodynamics. iii. Use the values for the heat capacity of water between 0C and 30C that are attached. Plot the heat capacity as a function of temperature (Excel!) and perform a second degree polynomial fit. Use the equation from the polynomial fit for the further calculations.

iv. Calculate the change in entropy, S, when heating water from 0C to 90C. v. Additionally, assume that the heat capacity is constant over this temperature range (0C to 90C) and calculate again S. (cp = 4.1818 J g-1 K -1)

vi. What do you need to consider if water is heated up to 150C (at 1 atm)? Sum up the relevant entropy changes to get the total entropy change (only the general equation, do not fill in any numbers).