CHE 112 Thermodynamics Practice
You may use Table of Thermodynamic Values.
1. For the following reaction, N2(g) + 3F2(g) à 2NF3(g), /\H° = -249 kJ & /\S° = -278 J/K
a) Find the temperature (if any) at which /\ G° equals zero.
b) Does the enthalpy change contribute to spontaneity? Explain.
c) Does the entropy change contribute to spontaneity to spontaneity? Explain.
d) Explain how reaction spontaneity depends on temperature. (Be specific: use actual temperatures...)
2. Consider the reaction CaCO3(s) == CaO(s) + CO2(g)
Use thermodynamic data to calculate the equilibrium pressure of CO2(g) at 25°C.
(for CaCO3(s), /\G°f = -1128.76 kJ/mole at 298K)
3. Consider the reaction N2H4(g) à N2(g) + 2H2(g) . If the partial pressures of N2H4(g), N2(g), H2(g) are 6.0, 0.0010, and 0.00020 atm respectively, find /\G for the reaction at 25°C. (Hint: First find /\ G°for the reaction.) ( /\G°f = 159.4 kJ/mole for N2H4(g))