AP EAMCET Engineering 2018 Apr 22 Shift 1 Paper

The reaction (I) is shown below.
CH3OH(l)+

3

2

O2(g) → CO2(g) + 2H2O(l) ; Δr H° = - 726 kJ mol−1
The reaction (II) is shown below.
H2(g)+

1

2

O2(g) → H2O(l) ; Δr H° = - 286 kJ mol−1
The reaction (III) is shown below.
C(graphite)+O2(g) → CO2(g) ; Δr H° = - 393 kJ mol−1
Multiply the reaction (III) by 2 .
From reaction (II)+(III)−(I), we can obtain the standard enthalpy formation of CH3OH(l)
−286×2−393−(−726)=ΔHf°
ΔHf°=−239kJ∕mol