Question

Consider the reaction: 2 BsHs (I)12 02 (g) (a) Use the standard enthalpies of formation found in Appendix B of the textbook to calculate the enthalpy change of the reaction. The standard enthalpy of formation of BsH, (I) is 73.2 kl/mol. 5 B2Os (s) +9 H2O (I) (b) Predict the sign of the entropy change and provide the two reasons likely to have made the biggest impact on the entropy change (and upon which you based your prediction). (c) Based on your answer for (a) and your prediction for (b), do you expect the reaction to be spontaneous at all temperatures, at high temperatures only, at low temperatures only, or not spontaneous at any temperature? Briefly explain. Write the reaction equation for which the enthalpy change would be the enthalpy of formation of Fe(NOs)s (s). 3. 4. Given the following information, 2 H2 (8)+ O2 (g) 2 H20 (B) 3 O2 (8)2O3 (g) AH-483.6 kJ/mol AH +284.6 kl/mol what is the AH for the reaction 3 H2 (g) + 03 (g) 3 H20 (g)?

Answer 1

w 2 B5 Hq W) + 12021g) 5 6,03 () +942044) L DO Head PPPPPPPPPLE (6) a tigo de rock up second thing ( ale taxat - (2x Aty Beta + 12 xDF ) (5x-1272.77 + 9x - 285-83) - (ax 73.2 +12x0) = -8936.32 - 1464 TOHg = 9082.72 wfl The entropy is possibly decreasing So entropy change is vel Becoz i) The no. of gaseous moles on the product side is far less than on the reactant side No prod <44 greactant. Garcous moles are highly entropic than other 2) Reactants side has liquid & gaseops species But products side has solid. (which has very Entopy Solid es liquid ce Gas. less entropy

46 - DH - TAS Aho is are and of high magnitude Aso is ve So, ag - -|AH'I + Tla sol Reaction is spontaneous only if AG 20. So - 1AHI+T/As I should be co Then, Tlas 1 < 1AHI Ta JAHI JASO Soy reaction is spontaneous only at low temperatures However if at higher temp., A 70 Then it's not spontaneous. Fe + 4HNO3 Fe(NO3)₂ + NO + 2H20 4) (2H₂ +0, 2420 ) x 3% AH = -483.6 ufus & 3/2 + (30249) 203) X-/ ut 284.6 kg. x - 1/2 3H2 +03 3H₂O AH =-867.7 us