Department of Metallurgical and Materials Engineering
Indian Institute of Technology Kharagpur
Assignment 2
Subject: Metallurgical Thermodynamics and Kinetics (MT21105)
1. A stoichiometric mixture of 𝑁2(𝑔) and 𝐻2(𝑔) at 100 atm and 800 K enter a catalytic
reactor for the synthesis of ammonia (𝑁𝐻3). Calculate the equilibrium composition of the gas
mixture. Also, calculate the equilibrium composition of the gas mixture for the following
conditions
(i) Temperature is increased to 1000K, while the pressure is kept constant at 100 atm.
(ii) Pressure is increased to 150 atm, while the temperature is kept constant at 800K
Given: 𝑁2(𝑔) + 3𝐻2(𝑔) = 2𝑁𝐻3(𝑔)
𝛥𝐺0 = -24, 100 + 53.4𝑇𝑐𝑎𝑙
2. (a) Calculate the partial pressure of monoatomic nitrogen in nitrogen gas at 2500 K and 1
atm.
(b) Calculate the total pressure of the gas at 2500 K when the partial pressure of N2 is 80% of
the total pressure.
Given: N2(g) = 2N(g)
ΔGT0 = 945000 - 114.9 T J
3. Two of the oxides of iron are FeO and Fe3O4. Solid Fe exists in equilibrium with one of
these oxides at low temperatures and exists in equilibrium with the other oxide at high
temperatures.
The molar free energies of formation of these oxides are
Fe(s) + ½ O2(g) = FeO(s)
∆Go = - 259,600 + 62.55 T joules
3Fe(s) + 2O2(g) = Fe3O4(s)
∆Go = - 1,091,000 +312.8 T joules
Determine which of the two oxides is in equilibrium with iron at room temperature and the
maximum temperature at which this oxide is in equilibrium with iron.
4. Three equations for the oxidation of Mg are
Mg + ½ O2(g) = MgO(s)
Mg + ½ O2(g) = MgO(s)
Mg + ½ O2(g) = MgO(s)
∆Go = - 604,000 - 5.36 T ln T + 142.0 T joules (I)
∆Go = - 759,800 - 13.4T ln T + 317 T joules (II)
∆Go = - 608,100 - 0.44 T ln T + 112.8 T joules (III)
One of these equations is for the oxidation of solid Mg, one is for the oxidation of liquid Mg,
and one is for the oxidation of gaseous Mg. Determine which equation is for which oxidation,
and calculate the melting and normal boiling temperatures of Mg.