//Engineering and Chemical Thermodynamics //Example 2.13 //Page no :73 clear ; clc ; //Given data : del_h0_f_CO2 = -393.51 ; //[kJ/mol], From Appendix A.3 del_h0_f_CO = -110.53 ; //[kJ/mol], From Appendix A.3 del_h0_f_H2O = -241.82 ; //[kJ/mol], From Appendix A.3 del_h0_f_C3H8 = -103.85 ; //[kJ/mol], From Appendix A.3 del_h0_f_O2 = 0 ; //[kJ/mol], From Appendix A.3 A_CO2 = 5.457 ; // From table E2.13 B_CO2 = 1.05 * 10^-3 ; D_CO2 = -1.16 * 10^5 ; A_CO = 3.379 ; B_CO = 5.57 * 10^-4; D_CO = -3.1 * 10^3 ; A_H2O = 3.470 ; B_H2O = 1.45 * 10^-3; D_H2O = 1.21 * 10^4 ; A_N2 = 3.280 ; B_N2 = 5.93 * 10^-4; D_N2 = 4.00 * 10^3 ; //Let n_C3H8 = 10 ; //[mol] n_N2 = (0.79/0.21) * (9.7/2) * n_C3H8 ; //[mol] n_CO2 = 2.7 * n_C3H8 ; //[mol] n_CO = 0.3 * n_C3H8 ; //[mol] n_H2O = 4 * n_C3H8 ; //[mol] n_O2 = (9.7 / 2)* n_C3H8 ; //[mol] T_reff = 298 ; //[K] del_H_rxn_298 = n_CO2 * del_h0_f_CO2 + n_CO * del_h0_f_CO + n_H2O * del_h0_f_H2O - n_C3H8 * del_h0_f_C3H8 - n_O2 * del_h0_f_O2 ; //[kJ] //The co-efficients of T2 in the equation of degree 3 are a = 8.314*(n_CO2 * (B_CO2/2) + n_CO * (B_CO/2) + n_H2O * (B_H2O/2) + n_N2 * (B_N2/2)); b = 8.314*(n_CO2 * A_CO2 + n_CO * A_CO + n_H2O * A_H2O + n_N2 * A_N2) ; d =8.314*(- n_CO2 * D_CO2 - n_CO * D_CO - n_H2O * D_H2O -n_N2 * D_N2) ; c = (del_H_rxn_298 *1000) + 8.314 * (n_CO2 * (- T_reff * A_CO2 - B_CO2/2 * T_reff^2 + D_CO2/T_reff) + n_CO * (- T_reff * A_CO - B_CO/2 * T_reff^2 + D_CO/T_reff) + n_H2O * (- T_reff * A_H2O - B_H2O/2 * T_reff^2 + D_H2O/T_reff) + n_N2 * (-T_reff * A_N2 - B_N2/2 * T_reff^2 + D_N2/T_reff)); T2=poly(0,'T2'); P = d + c*T2 + b*T2^2 + a*T2^3 ; M = roots(P); disp(" Example: 2.13 Page no : 73") ; disp(" The roots of the equation containig T2 as variable are (K)-") disp(M); disp(" But T2 must be more than 298K . So we have to choose the most suitable solution .") // The answer in the textbook does not statisfy the equation while it is counter-checked .