BITSAT2023ChemistryThermodynamics (C)Actual
If enthalpies of formation of C ₂ H ₄( ~g ), CO ₂( ~g ) and H ₂ O ( l ) at 25^ C and 1 ~atm pressure are 52,394 and -286 ~kJ / mol respectively, the change in enthalpy for combustion of C ₂ H ₄ is equal to
Options
- A-141.2 ~kJ / mol
- B-1412 ~kJ / mol
- C+14.2 ~kJ / mol
- D+1412 ~kJ / mol
Correct answer
B. -1412 ~kJ / mol
Step-by-step solution
Enthalpy of formation of C ₂ H ₄, CO ₂ and H ₂ O are 52,-394 and -286 ~kJ / mol respectively. (Given) The reaction is C ₂ H ₄+3 O ₂ 2 CO ₂+2 H ₂ O change in enthalpy, ( H)= H_ products - H_ reactants =2 (-394)+2 (-286)-(52+0) =-1412 ~kJ / mol .