Question

Calculate the equilibrium constant (KP) for the reaction forming ammonia at 700 K and 1 bar(3/2) H2 (g) + (1/2) N2 (g)  NH3 (g)by using partition functions. Use the following molecular information: m (NH3) = 17.024 amu, m (H2) = 2.016 amu, and m (N2) = 28.0 amu. The rotational constants of NH3 are 9.44, 9.44, and 6.2 cm-1, and its vibrational constants (and degeneracies) are 3336 (1), 932 (1), 3443 (2), and 1616 (2) cm-1. Rotational and vibrational temperatures for H2 and N2 can be taken from Table 18.2. The ground electronic states of all three species have degeneracies of 1. Calculate the relative energies of the substances in two ways: a) use the D0 values in Tables 18.2 and 18.4 and b) compare this with the value you can extract directly from Table 24.4. Once you have calculated KP, compare this value to the one you can determine from (delta)fG_700(NH3,g) that you can look up in Table 26.4. Also compare your value for the partition function of NH3(g) with one you can calculate from the ((delta)G_700-H_0)(NH3,g) value you can determine from Table 26.4.