Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 11-science Answered

The combustion of one mole of ethanol takes place at 298 K and 15 atm .After combustion,CO2(g) and H2O(l) are produced and 1365.6Kj of heat is liberated .CAlculate the standard enthalpy of formation  H of ethanol. Standard enthalpies of CO2 and H2O are -393.5Kj/mol and -285.83Kj/mol respectively. meritnation
Asked by Ibrahim Mohammed | 23 Feb, 2015, 10:51: PM
answered-by-expert Expert Answer

Formation reaction for ethanol is given as:

 

2C(S) + 3H2(g) + (1/2) O2(g) → C2H5OH(l)                       ΔfH = ?                                  ….. (i)

 

The enthalpy of combustion of 1 mole of ethanol is,

 

C2H5OH(l) +  3O2(g) → 2CO2(g) + 3H2O                          ΔCH = -1365.6 kJ                ….. (ii)

 

The enthalpy of formation of 1 mole of CO2 is,

 

 C(S) + O2(g) → CO2(g)                                                         ΔfH = -393.5 kJ / mol       ….. (iii)

 

The enthalpy of formation of 1 mole of H2O is,

 

H2(g) + (1/2) O2(g) → H2O(l)                                              ΔfH = -285.83 kJ / mol     ….. (iv)

 

Multiply eq. (iii) by 2 & (iv) by 3 we will get,

 

2C(S) + 2O2(g) → 2CO2(g)                                                   ΔfH = -787 kJ / mol           ….. (v)

 

3H2(g) + (3/2) O2(g) → 3H2O(l)                                         ΔfH = -857.49 kJ / mol     ….. (vi)

 

Add (v) & (vi),

 

2C(S) + 3H2(g) + (7/2)O2(g) → 2CO2(g) + 3H2O(l)           ΔfH = -1644.49 kJ / mol   ….. (vii)

 

Now, reverse eq (ii),

 

2CO2(g) + 3H2O → C2H5OH(l) +  3O2(g)                          ΔCH = 1365.6 kJ                  ….. (viii)

 

Add (vii) & (viii), we will get,

 

2C(S) + 3H2(g) + (1/2) O2(g) → C2H5OH(l)                       ΔfH = 278.89 kJ / mol

Answered by Arvind Diwale | 24 Feb, 2015, 01:59: PM
CBSE 11-science - Chemistry
Asked by rukayabatool395 | 24 Mar, 2024, 07:48: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Chemistry
Asked by mankdubey670 | 06 Jun, 2022, 01:27: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Chemistry
Asked by rama26516 | 12 Mar, 2022, 01:49: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Chemistry
Asked by advssdrall | 11 Jan, 2022, 07:44: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Chemistry
Asked by mossewalasindhu | 20 Nov, 2021, 02:16: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Chemistry
Asked by chandankumargochhayat6 | 19 May, 2021, 08:48: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Chemistry
Asked by paulnaveed202 | 17 Dec, 2020, 12:36: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Chemistry
Asked by kjay0981 | 13 Dec, 2020, 03:45: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 11-science - Chemistry
Asked by adityasolanki7773 | 22 Oct, 2020, 03:40: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
Get Latest Study Material for Academic year 24-25 Click here
×