Calculate the standard enthalpy of combustion of CH3COOH(l) from the following data: - Chemistry

Calculate the standard enthalpy of combustion of CH3COOH(l) from the following data:

Delta_fH^@(CO_2)=-393.3 kJ mol^-1

Delta_fH^@(H_2O)=-285.8 kJ mol^-1

Delta_fH^@(CH_3COOH)=-483.2 kJ mol^-1

Solution

C_((s))+O_(2(g))->CO_(2(g))                                     Delta_fH^@=-393.3 kJ mol^-1...(1)

H_(2(g))+1/2O_(2(g))->H_2O_((l))                               Delta_fH^@=-285.8 kJ mol^-1...(2)

2C_((s))+2H_(2(g))+O_(2(g))->CH_3COOH        Delta_fH^@=-483.2 kJ mol^-1 ...(3)

The required equation is,
CH3COOH(l) + 2O2(g) →2CO2(g) + 2H2O(l)

Multiplying equation (1) and equation (2) by 2, then adding to reverse of equation (3).

2C_((s))+2O_(2(g))->2CO_(2(g))                                  Delta_fH^@=-786.6 kJ mol^-1

2H_(2(g))+1O_(2(g))->2H_2O_((l))                               Delta_fH^@=-571.6 kJ mol^-1

CH_3COOH_(l)->2C_((s))+2H_(2(g))+O_(2(g))          Delta_fH^@= 483.2 kJ mol^-1

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CH_3COOH_(l)+2O_(2(g))->2CO_(2(g))+2H_2O_((l))          Delta_fH^@=-875 kJ mol^-1

Concept: Chemical Thermodynamics and Energetic - Enthalpy of Bond Dissociation
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