Standard enthalpy of formation for acetic acid at 25 degrees C?

standard heat of combustion of acetic acid is -874.5kjmol^-1


dHf for:





Co2: -393.5


C: 0


H2: 0


H2O: -285.83


CO2:0


CH3COOH: ?





all values taken at 298K= 25degrees C


CH3COOh+2O2= 2CO2+2H2O

Standard enthalpy of formation for acetic acid at 25 degrees C?
1 CH3COOH + 2 O2 --%26gt; 2 CO2 + 2 H2O





-874.5 kJ = prod - reactants





-874.5 kJ = ( 2 CO2 %26amp; 2 H2O) - (1 CH3COOH %26amp; 2 O2)





-874.5 kJ = ( -787.0 %26amp; -571.66) - (1 CH3COOH %26amp; zero)





-874.5 kJ = (-1358.66) - ( CH3COOH)





-874.5 kJ + 1358.66 = - ( CH3COOH)





484.16 = - ( CH3COOH)





ANSWER CH3COOH = - 484.2 kilojoules














vs Std enthalpy of formation liquid −483.5 kJ/mol