The standard enthalpies of formation in KJ mol-1 for CO2(g) , H2O(l) and C2H5OH(l) are -393.5, - 286.0 and -278.0 respectively. The standard enthalpy of combustion of C2H5OH(l) in kJ mol-1 is

Question

The standard enthalpies of formation in KJ mol-1 for CO2(g) , H2O(l) and C2H5OH(l) are -393.5, - 286.0 and -278.0 respectively. The standard enthalpy of combustion of C2H5OH(l) in kJ mol-1 is (A)  -923  (B)  +1367  (C)  +1923  (D)  -1367

Tardigrade Admin · Accepted Answer

C(s)+O2(g) → CO2(g), Δ H =-393.5 kJ mol-1 dots (i) H2(g)+(1/2)O2(g) → H2O(l), Δ H=-393.5 kJ mol-1 dots(ii) 2C(s)+3H2(g)+(1/2)O2(g) → C2H5OH(l), Δ H =-278.0 KJ mol-1 dots (iii) C2H5OH(l)+3O2(g) → 2CO2(g)+3H2O(l), Δ H=? dots(iv) (i)× 2+3× (ii) - (iii) will give equation (iv) Hence, Δ Hcombustion=2(-393.5)+3(-286)-(-278) =-787-858+278 =-1367 KJ mol-1

Q. The standard enthalpies of formation in $K J m o l^{- 1}$ for $C O_{2} (g)$ , $H_{2} O_{(l)}$ and $C_{2} H_{5} O H_{(l)}$ are $- 393.5, - 286.0$ and $- 278.0$ respectively. The standard enthalpy of combustion of $C_{2} H_{5} O H_{(l)}$ in $k J m o l^{- 1}$ is

$- 923$

$+ 1367$

$+ 1923$

$- 1367$

Q. The standard enthalpies of formation in KJmol−1 for CO2​(g) , H2​O(l)​ and C2​H5​OH(l)​ are −393.5,−286.0 and −278.0 respectively. The standard enthalpy of combustion of C2​H5​OH(l)​ in kJmol−1 is

−923

+1367

+1923

−1367

Q. The standard enthalpies of formation in $K J m o l^{- 1}$ for $C O_{2} (g)$ , $H_{2} O_{(l)}$ and $C_{2} H_{5} O H_{(l)}$ are $- 393.5, - 286.0$ and $- 278.0$ respectively. The standard enthalpy of combustion of $C_{2} H_{5} O H_{(l)}$ in $k J m o l^{- 1}$ is

$- 923$

$+ 1367$

$+ 1923$

$- 1367$