## Info

Find the coefficient of:

(a) Thermal expansion at 50°C and 25 MPa.

(b) Compressibility at 50°C and 40 MPa.

2.24 An adiabatic vessel contains 1 mole of subcooled liquid tin at 495 K. Scratching the vessel wall causes the tin to revert to its-equilibrium melting temperature of 505 K, accompanied by solidification of a fraction/of the liquid. Determine/using the following physical data for tin:

Heat of fusion = 7.1 kJ/mole

Hint: Use a two-step path for the process: one temperature-increase step at constant fraction solid and one isothermal step during which solidification occurs. It does not matter in which order these steps are taken. An efficient method of treating these paths is to first derive the formulas for h£T) and hL(T).

2.25 An elemental solid has a heat capacity of 1 J/g-K. What is the atomic weight of the element?

2.26 Consider the tin-crystallization process of Problem 2.24.

(a) Is the entropy change positive or negative? Explain your reasoning.

(b) Write the equations for the temperature dependences of the entropies of the liquid and solid.

(c) Calculate the entropy change for both paths.

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