Question

Sulfur dioxide, SO2(g), can react with oxygen to produce sulfur trioxide, SO3(g), by the reaction 2 50, (g) + O2(g) 250, (g) The standard enthalpies of formation for SO2(g) and SO2(g) are AH (SO2(g)] = –296.8 kJ/mol AH (SO2(g)] = -395.7 kJ/mol Calculate the amount of energy in the form of heat that is produced when a volume of 1.09 L of So, (g) is converted to 1.09 L of So, (g) according to this process at a constant pressure and temperature of 1.00 bar and 25.0 °C. Assume ideal gas behavior. AH= 14.835 kJ

Answer 1

Standard enthalpies of formation AHºt( s02 (g) ) = -296.8 kJ/mol AHºfl 02 (g) ) = 0.0 kJ/mol AH°:( SO3 (g) ) = -395.7 kJ/mol 2 SO2(g) + 1 02 (g) → 2 S03 (8) AHºreactents = ( 2 % -296.8 )+( 1 x 0 ) = -593.6 kJ/mol AH°products = ( 2 * -395.7 )= -791.4 kJ/mol ΔΗχη = ΔΗ°products -ΔΗ°reactents AHrxn = ( -791.4 )-( -593.6 ) = -197.8 kJ 1 barr= 0.987 atm Calculating number of moles: Pressure of SO2 = P = 1.000 barr Pressure of SO2 = P = 0.987 atm Volume of SO2 = V = 1.090 L number of moles of SO2 = n = ? mol Gas Constant = R = 0.0821 L.atm/mol.K temperature = L = 25 °C = 25 + 273 Ideal gas equation PV = nRT = 298.0 K n = _ PV RT ( 0.987 )( 1.090 ) (0.0821 )( 298 ) number of moles of SO2 = n = 0.0440 mol 2 Moles of SO2 releases 197.8 kJ of energy 0.0440 Moles of SO2 releases – 197.8 x 0.04 = 4.349 kJ of energy 2 | AH = 4.35 kJ