Use the data from this table of thermodynamic properties to calculate the values of ΔS°rxn for each of the following reactions at 25 °C.

A) 4NH3 (g) + 7O2 (g) - --> 4NO2 (g) + 6H2O (g) Delta S rxn = ?

B) 2H2O2 (l) - -> 2H2O (l) + O2 (g) Delta S rxn = ?

A) ΔSºrxn = - 112.5 J/molK

B) ΔSºrxn = - 120.48 J/molK

Explanation:

For an general equation aA + bB → cC + dD

ΔSºrxn = cSºC + dSºD - aSºA - bSºB

Using a table of thermodynamic properties in J/molK like Petrucci 8th Ed

A) ΔSºrxn = (4*240,1) + (6*188,8) - (4*192,5) - (7*205,1) = - 112.5 J/molK

B) ΔSºrxn = (2*69,91) + (1*205,1) - (2*232,7) = - 120.48 J/molK

Be careful with the states of matter