Question

Calculate the standard enthalpy change for the following reaction at 298 K using the standard enthalpies of formation:2SO2(g) + O2(g) → 2SO3(g)

Answer 1

To calculate the standard enthalpy change  H  for the reaction, we can use the following equation:H =  [Hf products ] -  [Hf reactants ]where Hf is the standard enthalpy of formation for each substance.The standard enthalpies of formation  Hf  for the substances involved in the reaction are as follows  in kJ/mol :SO2 g : -296.8 kJ/molO2 g : 0 kJ/mol  since it's an element in its standard state SO3 g : -395.7 kJ/molNow, we can plug these values into the equation:H = [2   -395.7 kJ/mol ] - [2   -296.8 kJ/mol  + 1  0 kJ/mol]H =  -791.4 kJ  -  -593.6 kJ H = -197.8 kJSo, the standard enthalpy change for the reaction at 298 K is -197.8 kJ.