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COMEDK2023ChemistryThermodynamics (C)

If 2 moles of C ₆ H ₆( ~g ) are completely burnt 4100 ~kJ of heat is liberated. If H^ for CO ₂( ~g ) and H ₂ O (l) are -410 and -285 ~kJ per mole respectively then the heat of formation of C ₂ H ₆( ~g ) is

Options

  1. A-116 ~kJ
  2. B-375 ~kJ
  3. C-775 ~kJ
  4. D-885 ~kJ

Correct answer

B. -375 ~kJ

Step-by-step solution

array r 2 C ₂ H ₆(g)+7 O ₂(g) 4 CO ₂(g)+6 H ₂ O (l) ; H=-4100 ~kJ array Let, H_f^ ( C ₂ H ₆ )=x , aligned H & = H_ f( products ) ^ - H_ f_ ( reactants ) ^ ^ -4100 & =[4(-410)+6(-285)]-[2 x+0] x & =-375 ~kJ aligned

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